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f 




BRANNER 
GEOLOGICAL LIBRARY 




f 



\z--:-/p^-v' -'•::--:'^^^^^\ 




GREAT NEAPOLITAN EARTHQUAKE OF 1857. 



'\\ 



r.i'XIK)*' FBINTKD Irt WILLIAM t■lJf»H^J* AKIt MiS.-. .-TAMMiKH MKI.I.T AM) CHAIIIK*! ^R»^^^. 




i 



"i 




GREAT NEAPOLITAN EARTHQUAKE OF 1857. 



THE FIRST PRmCIPLES 



OK 



OBSERVATIONAL SEISMOLOGY 



AS DEVELOPKD IN THE 

IlEPORT TO THE ROY AT. SOCIETY OF LONDON 

OF Tire EXPEDITION MADE BY COMMAND OF THE SOCIETY INTO 

THE INTERIOR OF THE KINODOM OF NAPLES. 

TO INVESTIGATE THE CIRCUMSTANCES OF THE GREAT 
EARTHQUAKE OF DFXJEMBER 1857. 

ROBEllT MAJ.LET, C.E., F.R.S, F.G.S., »LR.I.A., 

■^" &C., &C. 



'* Ncn /ingGodum out cxcogitiiiuIuTn sed invmiondum quid natura HiciAt aut fcrat.' 



PrBLlSttED Itr THE AUTH0RTT7 AND WITH THE AID OF THK 

ROYAL SOCIETY OF LONDON. 



IN TWO VOLUMES.— VOL. I. 



CHAPMAN AND HALL, LONDON. 

1862. 

jf7if Uhiltt of Trunyiai'nni in rt-nerrtiJ. 



L -i" ' 



213535 



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< • 



• • • 



• • 












« • • 

9 
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• • • 






• • 




DEDICATION. 



To THE Rev^- T. R. Robinson, D.D., F.R.S., &c., 

AsTRON. DiR. Armagh. 

My dear Sir, 

Friendship, unbroken since my boyhood, and the 
many occasions upon which you have encouraged or 
assisted such attempts as I have made to advance know- 
ledge, alone would induce me, with affectionate regard, 
to dignify these Volumes by connecting them with your 
own distinguished name; but to whom else could I so 
properly inscribe them, for to your early recognition 
of those truths which I had enunciated as the foundations 
of the science of Seismology, and to your prompt and 
weighty advocacy, of the importance to science, of seizing 
the opportunity of the great Neapolitan shock to apply 
those principles to nature, these Volumes probably owe 
their existence. 

Ever, with much esteem, 
I am yours, 

Robert Mali.et. 

London, Ut October, 18G2. ^ 



PREFACE. 



Some explanation seems desirable of how it is that the 
following Report to the Royal Society of London appears 
in form of the present volumes, and why not at an earlier 
period. 

The earthquake of December, 1857, by almost the first 
notices that reached England, revealed itself as the third 
greatest in extent and severity of which there is any 
record as having occurred in Europe. 

Impressed with its observational value to science, the 
Author at once addressed the following letter to the then 
President of the Royal Society : — 

" Delyille, Glasnevik, Co. Dubun, 
" 2Sih December, 1867. 

•* My Lord, 

^^ The very recent occurrence of a great earthquake 
in the Neapolitan territory presents an opportunity of the 
highest interest and value for the advancement of this 
branch of Terrestrial Physics. 

"Within the last ten years only Seismology has taken its 
place in cosmic science — and up to this time no earthquake 
has had its secondary or resultant phenomena — sought 



viii PREFACE. 

for, observed, and discussed by a competent investigator 
— by one conversant with the dynamic laws of the hidden 
forces we are called upon to ascertain by means of the 
more or less permanent traces they have left, as 
Phenomena, upon the shaken territory. 

^* Observed without such guiding light, or often passed 
by unnoticed and undiscovered for want of it — the facts 
hitherto recorded are in great part valueless — but with 
this guide such investigation is capable of results of high 
importance. Thus it was that Dolomieu's elaborate 
record of the eflTects of the great Calabrian Earthquake is 
of so much less value than it might have been. 

* Earthquake observations are of two classes — those 
which must be made before and at the moment of shock 
(time and space measurements chiefly) and those which 
may be made at a recent period after it. To the latter 
belong those nimierous and instructive fects treated or 
under the heads of Secondary and Accidental Phenomena 
in my First Report on the Facts of Earthquakes (^ Reports 
Brit. Ass. 1 850 *), and also in the ^Admiralty Manual ' — as 
well as many questions treated of under heads 1 5 ^ to 24 ' 
of the former. In those papers I have stated some of the 
methods of observation — of shattered buildings — altered 
water courses and springs — changed relations of level and 
position — localities of maximum and minimum dis- 
turbance — their relations to origin — to formation, &c., &c., 
and the inferences deducible. I need not, therefore, 
dilate upon them here, 

^* I have long looked for the occurrence of an oppor- 
tunity so favourable for inquiry as that which has been 



PREFACE. ix 

just presented. It is one so rare, and in so peculiar and 
suggestive a region, that 1 venture to urge, through your 
Lordship, the Royal Society, that it should not be 
permitted to be lost to Science. To avoid this, however, 
the examination must be made with all possible jt?rampri- 
tudey as every hour alters or removes the characters of the 
terrible inscription which we are to decipher, and renders 
circumstantial, local, and oral evidence less trustworthy. 

" I respectfully oflTer, my Lord, if such be the will of 
the Royal Society, to proceed at once to Naples and the 
shaken regions, to collect, discuss, and report the facts. 
I am prepared to devote a month or five weeks to the 
inquiry, which, allowing ten days to the journey, to and 
from the city of Naples, I deem sufficient, if energetically 
and well employed. 

^^Were I a wealthy man I should proceed instantly, 
* and on my own responsibility ; but, although willing to 
give one-twelfth of my professional time and income for 
1858 to it, private duties make it unsuitable that I should 
also be at the necessary expenditure for the journey and 
local inquiry. 

* For this a sum of about One Hundred and Fifty 
Pounds would, I consider, be required, as the aid of local 
assistants, interpreters, with the peasantry, and the means 
of rapidly moving in remote and little frequented places 
(such as Basilicata), with other accessory charges, must 
be provided for. The best maps and all requisite instru- 
.ments I am prepared with. 

*^ In the humble but earnest confidence that I can in 
this do good service to Science, I submit to the Royal 



X PREFACE. 

Society whether it see fit to make such a grant, and to 
entrust the work to me ; if so, I should be prepared to set 
out by the middle of next month. 

" I have the honour to be, My Lord, 

" Your very obedient Servant, 

"Robert Mallet. 



The Lord Wrottesley, President, 
" Bayed Society, London" 



The writer's views were promptly laid by the President 
before the Council of the Royal Society, where they were 
supported by the advocacy of Doctor Robinson, General 
Sabine, Sir Charles Ly^U, Sir Roderick I. Murchison, 
and others. In result the Author was requested to 
proceed with the inquiry, and a grant made of the entire 
sum asked for. This amount proved, in the end, inade- 
quate, as did also the period of time which it was 
proposed to devote to the investigation; so that the 
Author himself defrayed about two-fifths of the entire 
cost of the expedition, and found it necessary to devote to 
jt more than double the time he intended beforehand. 
A further sum of Fifty Pounds toward procuring the 
Photographs, fi'om which many of the Illustrations of 
these volumes have been reproduced, was voted by the 
Royal Society after the Author s departure, and the fact 
was communicated to him by telegraph. 

A comparatively small proportion of the large collec- 
tion of scientifically valuable Photographs made in the 
convulsed regions have been now reproduced, the limi- 



PREFACE. xi 

tation having been due to cost of production. The whole, 
however, are referred to by number in the text, those 
omitted with the addition (C!oll. Roy. Soc.) ; and the ori- 
ginals may be consulted by Seismologists in the Library 
of the Royal Society, where the entire collection made, is 
now preserved along with the original sketches, maps, and 
manuscript. 

Within a week of the Author's return to England in 
April, 1858, he addressed a preliminary Report to the 
President and Council of the Royal Society, the nature of 
which may be seen by the following extract from its 
introductory sentences : — 

^ On my return from the expedition of observation in 
the earthquake-shaken provinces of Naples, entrusted to 
me by the Royal Society, it becomes my duty to report 
briefly to your Lordship as President, and to the CJouncil, 
where I have been, what I have done, and what of value 
to science, I may conceive myself to have accomplished ; 
reserving scientific details and deductions to a separate and 
more systematic communication, which I hope ere long to 
have the honour of laying before the Royal Society, and 
which will embrace the results of my inquiries." 

Two years nearly elapsed before the Author, inter- 
rupted frequently through necessity of professional avo- 
cation, and by other events, was enabled to complete the 
laborious work of reducing his observations, involving 
much tedious calculation, expanding and writing out his 
field notes, colligating his results, and finally bringing 



xii PREFACE. 

his Report into the form in which it was presented and 
read to the Royal Society on the 24th May, 1860, and 
which is substantially that in which it now appears in the 
following pages. 

A brief abstract of the Report was published in the 
^ Proceedings Roy, Soc. Lon.,' vol. x. p. 486, &c,, and 
the document itself, with its accompanying maps, dia- 
grams, sketches, and photographs, ordered to be referred 
for publication. 

As to the mode of this, some difficulty arose. The 
Report, although in a great degree dealing with dy- 
namical and other rigid questions, is partly an inductive 
argument ; and hence, being necessarily of the nature of 
a jnece justicatify requires the sufficient statement of a 
number of directly employed facts ; besides and related 
to which were, many observations made en passant^ upon 
the physical features, geology, and other collateral 
subjects, which, referring to a country so little explored as 
the interior of the Neapolitan kingdom, it was not 
desirable to suppress. 

Its bulk thus became such that if published by the 
Royal Society in what might seem its natural place, it 
would have occupied an entire volume of the ^Philo- 
sophical Transactions,' to the exclusion, for the time, of 
all other papers, however valuable. Some suggestions 
were made to divide the Report, publishing in the ' Phi- 
losophical Transactions ' only its rigid mechanical por- 
tions in result, leaving the remainder for publication there 



PREFACE. xiii 

in future years; but to this the Author felt much objec- 
tion. 

Finally, the Council of the Royal Society, in the exercise 
of a wise discretion, and in a very liberal spirit, decided to 
devote a sum of three hundred pounds towards the cost 
of illustration, and proposed to the Author that he 
should publish, in extenso, his Report as a distinct and 
independent work. 

In pursuance of this, the Author arranged with Messrs. 
Chapman and Hall for publication in the form in which 
the work now appears, the Publishers having undertaken 
to defray the entire expense over and above the grant 
made by the Royal Society. Liberal as the amount of 
that was, it was not nearly sufficient for its object, owing 
to the great expenditure involved in the production of 
volum& illustrated as these are. The Author can but 
hope that the spirit with which the Publishers have thus 
shown themselves ready substantially to aid in pro- 
moting science, may not be to them profitless. 

It was midsummer last, before all these preliminaries 
admitted of the work being placed in the hands of the 
printer, and the illustrations in those of Mr. V. Brooks 
for lithographing. Practically, the whole was ready for 
publication early this year. For trade reasons the Pub- 
lishers requested that it might be postponed to the 
present time, to which the Author, though conscious of 
the long delay that circumstances had already imposed, 
readily assented. 



xiv PREFACE. 

These volumes, as they now appear, will probably be 
perused by two distinct classes. To the first, the really 
scientific reader, the Author will venture, though perhaps 
at the risk of some undeserved suspicion of egotism or 
vanity, to commend the subject and the method which 
they evolve, as pregnant with the power of future know- 
ledge, of the cosmical conditions of the interior of our 
own and of other planets ; that will be hereafter recognized 
as having first shown the way to any true intelligence 
from the viewless and unmeasured miles of matter beneath 
our feet ; and that will ere long give us up the key to 
the hitherto undeciphered enigma of vulcanicity. 

To the general reader, earthquake narratives have long 
shared in some degree, the charm that belongs to tales of 
shipwreck, of battle, or wild adventure, and ''perilous 
hair-breadth 'scapes " amidst natural phenomena the most 
tremendous : something of this he here will find i and 
though sobered to a reality not always found in earthquake 
stories, the events by which such multitudes perished, in 
which so many cities were overthrown, will be found by 
him who shall have even generally understood the prin- 
ciples here unfolded, to yield more intelligent pleasure, 
than the exaggerated and often fabulous phantasmagoria, 
of the older earthquake narratives, in the maze of which 
he wandered without any rational clue. 

He will here trace with interest the successive steps 
by which finally the depth of the focus, whence the im- 
pulse that produced the earthquake has* been for the 



PREFACE. XV 

first time ascertained, and measured in miles and yards 
with the certainty that belongs to an ordinary geodetic 
operation. 

It is of the nature of all science, to be but the portal 
to greater and higher truth beyond. Such is peculiarly 
the case with Seismology. The exact knowledge of 
earthquakes^ of their distribution in time and space, of 
their movements, results, and proximate causes, however 
interesting in themselves, are yet but means to an end. 

As palaeontology — itself dependent upon natural his- 
tory — lithology, and many other cognate knowledges, are 
but instruments of geology, so is seismology chiefly to be 
viewed and valued, as the instrument by which a know- 
ledge of the deep interior of our planet will be attained ; 
the only instrument yet discovered to this end, yet one 
possessed of vastly greater power and directness of aim, 
than any of those that physical geology has previously 
called to its aid. 

Though the youngest branch of cosmical science, it is 
to be regretted, that it has not been already better under- 
stood, and more applied by observational geologists, many 
of whom, had they mastered even its rudiments, might 
ere now have come laden with fruit from various 
regions. 

Physical geology, much as it owes to the labours, of the 
topographical and field geologist, to the patient observer 
and comparer of nature s superficial phenomena, can no 
longer rest satisfied with such modes of investigation 



xvi PREFACE. 

alone. The time has more than come, when it must 
devise new methods and new problems, and appropriate 
to their solution, all the aids that theoretical mechanics, 
including those of undulations, physics, and chemistry 
can afford ; and the geologist of the coming time, who 
shrinks from mastering these, though he may continue a 
labourer, shall be no ^^ light bearer " in the rising palace 
of cosmical truth. More or less, it is the Author s hope 
that these volumes may be ancillary to promoting and 
giving direction to such a result. 



Tjcndon, October, 1862. 



LIST OF ILLUSTRATIONS 



USED OR REFERRED TO 



IN THE FIRST VOLUME. 



Note. — In the following List of Illustbations, and in the text, wherever 
the reference is made in the words, " (Mlection of the Boyal Society,*^ or 
" OoU. Boy. iSbc.," it is to be nnderstood that such niastrations have 
been necessarily omitted from this work, in order to limit the expense 
of reproducing so great a nmnber of Photographs or Sketches, and 
that the originals of all such as are so omitted are to be found in the 
possession of the Boyal Sodeiy of London, 



%♦ For List of Maps see IHustrations to Vol. II. 

City of Polla after the Earthquake. — See No. 161 . Frontispiece 

Nnmber. Page. 

1. Woodcut Dahiel Bn. 10 

'> 16 

3. „ ........ V 18 

5. „ „ 18 

6. „ „ 20 

7. „ „ 20 

8. „ ........ „ 21 

O. „ ........ )| ^1 

10. Collection of the Royal Society 25 

11. n n ^G 

12. n n 27 

13. Castelluccio ^. Brooks, to face 29 

14. Padula „ 30 

14 his. Woodcut />ate«W Brs. 33 

VOL. I. h 



xviii LIST OP ILLUSTRATIONS. 

Nmnber* P^pe. 

15. Collection of the Royal Society 35 

^i» if ff •••} •. OO 

•18. „ „ 35 

19. „ ,, ....... 35 

20. n i» ••••... 35 

21. Woodcut Dalssid Brs, 88 

22. „ „ 38 

23. ff „ 38 

24. ,, ........ ,) 38 

25. Church at Pertosa, looking Korth-West . . F. Brooks, to face 42 

26. Woodcut Dcdzid Brs, 45 

27. „ „ 46 

28. „ „ 49 

29. „ „ 51 

80. Collection of the Bpyal Society 51 

81. Woodcut Dakid Brs. 53 

32. „ „ 63 

83. ,y ........ „ 53 

34. „ „ 53 

85. „ „ 60 

36. „ „ 59 

87. ^ „ 59 

OO. fi ........ y, 59 

39. „ „ 60 

40. „ „ 60 

41. „ „ 63 

42. „ „ 63 

43. n n 65 

44. t9 » 72 

46. , „ 67 

46. „ „ 68 

47. „ „ ? 73 

48. „ „ 66 

48 6w „ „ 69 

49. Auletta V, Brooks, to face 73 

50. The Cathedral, Patemo „ 74 

51. Collection of the Royal Society 74 

62. Woodcut Dalziel Brs, 76 

53. J, „ 76 

55. „ „ 77 

56. I, „ 77 



LIST OP ILLUSTRATIONS. xix 

Number. Pi^^ 

57. Woodcut DahidBn. 77 

58. „ „ 77 

C9. „ „ 86 

60. „ „ 87 

61. Cathedral of Marsico Nuovo, North sida — See 

page 42, vol. i V. Brooks. 

62. Santa Dommica, Montemnrro, looking South, 

from the Palazzo Fino „ 89 

63. At Polla „ 93 

64. Collection of the Boyal Society 93 

65. Woodcut DahidBn. 97 

66. Polla, Strada Eoroo V. Brooks^ to face 99 

67. Collection of the Royal Society 99 

68. „ „ ....... 99 

69. Woodcut ^ . DabBid Brs. 101 

70. „ „ 103 

71. „ , 108 

72. „ „ 103 

73. « 103 

71 „ 108 

75. „ „ 103 

76. „ „ 105 

77. „ „ 105 

78. „ „ 109 

79. „ „ 109 

80. Church at Pioemo. — See page 89, vol. L . . . V, Brcokn. 

81. Interior of the Cathedral at Tito, looking north- 

west. — See page 99, vol. L . . . . „ 

82. Collection of the Royal Society 114 

83. Church of the Madonna di Lorretto, Polla. — See 

No. 168, page 296, vol i F. Brooks 

84. Collection of the Royal Society 116 

oo. „ „ ...••.. 

86. Woodcut DahielBrs. 116 

87. „ . „ 117 

88. „ , 117 

89. „ , 118 

90. Collection of the Royal Society 118 

91. Woodcut DoMdBrs. U9 

92. „ , 120 

93. „ „ 125 

94. „ „ 126 

96. „ „ 127 



XX LIST OF ILLUSTRATIONS. 

Number. I'age. 

96. Woodcut Dahid Bra, 1*29 

97. „ „ 130 

98. „ . . .* „ 131 

99. „ „ 133 

100. „ „ 134 

101. „ ^ 135 

102. „ „ 135 

103. „ „ 140 

104. „ „ 145 

105. „ „ 155 

106. „ „ 155 

107. „ „ 158 

108. The Val di Diano, Town of Diano opposite . V, Brooks, tofaxe 165 

109. CJoUection of the Royal Society 165 

110. „ „ 169 

111. Woodcut DidzidBrs, 204 

112. „ „ 204 

113. „ „ 204 

•■■"'•*• »» ••«•.... „ 208 

115. „ „ 214 

116. „ „ 218 

117. „ ^ 218 

118. „ „ 225 

119. 

120. Vietri, near the New Road . . . . V, Brooks^ to face 232 

121. Woodcut Dahiel Brs, 234 

122. „ „ 234 

123. From the Plain of Pa»tum.— /See p. 272, vol i. . K. Brooks, 
124 

124 his. East Flank, Eboli ,,240 

125. West Flank, Eboli „ 240 

126. Collection of the Royal Society 242 

127. Woodcut Dahid Brs. 241 

128. „ „ 246 

129. „ „ 251 

130. „ „ 251 

131. „ „ 253 

132. Woodcut Dahid Brs. 256 

132 his. Auletta, showing the directions of the 

landslip and long fissures in the soil — Eye 

sketch K. Brooks, to face 257 

133. Collection of the Royal Society 258 

134. „ „ 260 



LIST OF ILLUSTRATIONS. xxi 

Nmnbcr. Pnge • 

135. Auletta F. Brooks^ to face 260 

136. At Auletta „ 260 

137. Woodcut Dahkl Brs. 262 

137 his. Villa Carnsso, near Auletta . . . F. Brocks^ to face 267 

138. The Porte Cochere, on the Military Road, Villa 

Carusso, near Auletta „ 270 

139. Woodcut DaUid Brs. 268 

140. „ „ 269 

141. „ „ 269 

X^A. }| ... «... yl iSiX 

143, Collection of the Royal Society 273 

145. The Flanks of Monte Albumo and Gastelluodo, 

near Auletta F. Brooks, to face 272 

146. Collection of the Royal Society 274 

147. „ „ 274 

148. „ „ 274 

149. „ „ 274 

*ou. }f jf ••••... £i^ 

151. Pertosa F. Brooks, to face 274 

152. Woodcut Ddlziel Brs, 275 

153. „ „ 279 

154. Section of the Valley at Pertoea . . . F. Brooks, to face 282 

155. Campostrina, Qorge of the Calore. Great Fall 

of Rock „ 286 

156. Campostrina „ 286 

157. Woodcut Dahiel Brs. 287 

158. FiflBurea on the Road near Polla . . . F. Brooks, to face 288 

159. Tenementa della Madonna, Campoetrina. — See 

page 274, vol. i „ 

160. Collection of the Royal Society 289 

161. {See Frontispiece) F. Brooks, 

162. Collection of the Royal Society 294 

163. „ „ 294 

164. „ „ 294 

165. „ „ 294 

166. „ „ 294 

167. Monastery of St. Claire, Polla, looking South- 

west F. Brooks, to face 295 

168. Church of the Madonna di Loretto, Polla . ,, 296 

169. Collection of the Royal Society 297 

170. Polla.r— Sec page 288, voL i F. Brooks. 

171. Collection of the Royal Society 298 



xxii LIST OF ILLUSTRATIONS. 

Number. Fuge. 

172. Collection of the Royal Society 298 

173. Small House by the River, Folia, looking west- 

ward F. Brooks^ to face 299 

174. Hoose on the Bank of the River, Folia, looking 

eastward „ 299 

175. Ghionnd Fkn of the Falazzo Falmieri . . „ 302 
175 his. Falazzo Falmieri at Folia .... „ 302 

176. Collection of the Royal Society 304 

177. Interior Fapade, Falazzo Falmieri, Folia, look- 

ing westward 303 

178. Interior Court, Falazzo Falmieri, Folia. — See 

page 286, voL i V, Brooks, 

179. Interior Court, Falazzo Fahnieri, Folia . . „ 303 

180. Collection of the Royal Society 304 

181. Woodcut ikikiel Brs. 306 

182. „ ........ „ 306 

183. Camine, Falazzo Falmieri, Folia, looking south. 

— See page 10, voL ii V. Brooks. 

184. Collection of the Royal Society 314 

185. „ „ 313 

186. „ „ 314 

187. Atena. — See page 286, vol. i V. Brooks, 

188i Atena „ 326 

189. Collection of the Royal Society 324 

190. A Street in Atena.— 5ee page 326, voL i. . . F. Brooks, 

191. Collection of the Royal Society 327 

192. „ „ 327 

193. Woodcut Dalzid Brs. 328 

194. „ n 330 

195. „ „ 330 

196. „ „ 333 

197. Collection of the Royal Society 334 

198. „ „ 335 

199. „ n 335 

200. Woodcut Dakid Brs, 338 

201. „ „ 339 

202. „ „ 339 

203. „ DdUidBrs. 341 

204. „ „ 342 

205. Collection of the Royal Society 341 

206. Woodcut— Church of La Sala Ddlziel Brs, 343 

207. Collection of the Royal Society 345 

208. Woodcut DalzielBrs. 347 



LIST OP ILLUSTRATIONS. xadii 

Number. FlBge. 

209. Collection of the Royal Society 349 

210. Valley to the east of La Sala— VaL di Diano . V. Brooks, to face 352 

211. Rock Aiguille, near Fadula .... „ 353 

212. „ fractured from its base . . „ 353 

213. Collection of the Royal Society 855 

214. „ „ 355 

215. „ „ 356 

216. Woodcut DalzidBrs. 356 

217. Overthrown Column, Palazzo Roman!, Padula. 

— See page 34, vol. ii F. Brooks, 

218. 

219. 

220. Collection of the Royal Society 362 

221. Woodcut Dahid Brs. 359 

222. „ „ 363 

223. „ ........ „ 866 

224. „ „ 367 

225. Monument of St. Bernard, at the Certosa, Padula V, BrookSy to face 870 

226. Collection of the Royal Society .- 371 

227. „ „ 371 

227J. „ „ 871 

228. „ n 372 

229. „ „ 373 

230. „ „ 373 

231. „ „ 373 

232. „ „ 373 

233. „ „ 373 

234. Grand Certosa, Padula. Interior of the Gallery 

of the Grand Court.— /Sec page 13, vol. ii. . . V, Brooks, 

235. Woodcut Dahid Brs. 378 

236. „ „ 379 

237. „ „ 380 

238. Diagram, The Campanile, Cistercian Monastery, 

Padula V, Brooks, to face 370 

239. Woodcut DahielBrs. 372 & 392 

240. Diagram, Cistercian Monastery, Padula . . V, Brooks, to face 370 

241. Diagram, Section from the Valley of the Calore 

to that of the Agri ^^ 373 

242. Diagram, Section from Spinosa to Viggiauo, 

across the Agri ^^ 403 

243. Collection of the Royal Society 411 

244. Woodcut DalzidBrs. 414 

245. „ „ 414 



xxiv LIST OF ILLUSTRATIONS. 

Nnmber. Pigo- 

246. Collection of the Royal Society 414 

247. „ „ 414 

248. Sarooni, Remains of the Church . . . V, Brooks^ to face 415 

249. Collection of the Royal Society 416 

250. Woodcut Dahid Brs. 415 

251. Saponara, with the remains of the Castello 

Cilliberti, looking Northward . . . F. Brooks^ to face. 419 

252. Sapobara, Remains of the Church. — See page 

415, vol. i. ...... . „ 

253. Mound of Rubbish where Saponara had been, 

looking Southward „ 419 

254. Collection of the Royal Society 420 

255. Saponara V, Brooks, to face 424 

256. „ „ 424 

257. Woodcut Dalzid Brs, 426 

258. Beds of the Agri and Moglia, Denudation of the 

Breccia. — See page 424, vol. i V. Brooks, 






INTRODUCTORY. 



On the 16th December, 1857, an earthquake of groat 
violence visited several of the southern provinces of the 
Neapolitan kingdom. Accounts of the formidable extent 
of the disaster, accompanied by a few imperfect details as 
to some of its physical phenomena, began to arrive in 
England, through correspondence and the public press, 
about the 24th December. The occasion appeared to the 
author to present an opportunity of observation of the 
highest value for the advancement of our knowledge of 
earthquakes, considered as a branch of cosmical science. 

On the 28th of the same month he accordingly addressed 
a letter to Lord Wrottesley, President of the Royal Society, 
suggesting the importance to science of sending a competent 
observer, without loss of time, to the convulsed region, 
and oflFering, with the approval and assistance of the 
Society, to undertake the duty. The suggestion was 
promptly laid before the Council by the President, met its 
approval, and on the 21st January, 1858, the author 
received the authority of the Royal Society to proceed. 

VOL. r. B 



• • • 

• • • 






• • . 



2 • ''•• PREPARATIONS IN LONDON. 

• • • 

./JPi^iii the 21st to the 26th January was occupied in 
dblaining letters and recommendations from the Council 
'and officers of the Royal Society, the British Minister for 
Foreign AflFairs, and some noble or eminent scientific 
persons in London, to the Grovernment of the kingdom of 
Naples, its well-known jealousy causing much doubt 
whether its permission might be obtained for the author 
to travel into the earthquake districts. 

On the 27th January the author left London, stopping 
a day at Paris, for the purpose of conferring with and 
receiving any suggestions that those there engaged in 
geological research might have to offer as to his intended 
labours ; and another at Dijon, in conference with Professor 
Perrey, the distinguished author of many works on seis- 
mology, with a like object. On the 5th February, 1858, 
he arrived at Naples, where he was detained until the 
10th, awaiting the tedious decision of the Neapolitan 
Government as to whether or not it would permit his 
journey into the interior. This permission was at length 
granted by telegraph from the king, then at Gaeta ; and, 
accompanied ultimately by letters of authority to the 
Intendenti, Judici, Syndici, and Gendarmerie of all the 
provinces proposed being traversed, enjoining them to give 
safe conduct and all possible assistance to the author and 
his objects. 

Before leaving England he had been favoured by 
Cardinal Wiseman with an encyclical letter, commending 
the object of his mission to the good offices of the clergy 
of all denominations in the interior. This valuable letter 
he was enabled, after an interview with the Cardinal 
(Sisto) Arelil)ishop of Naples, to get approved and coun- 



AT NAPLES. 3 

tersigned by that prelate ; and to that document he owes 
the removal of many difficulties that might otherwise 
have seriously impeded his progress and means of obser- 
vation. • 

The interval caused by the delay of the Neapolitan 
Government before granting its authorization to proceed, 
was occupied by the author, partly in providing, with the 
kind assistance of some British residents at Naples, a suit- 
able and trustworthy staff of persons to accompany him, 
and amongst these an interpreter who could converse readily 
in the provincial dialects of the Capitanatas, Basilicata, 
Ban, and Calabria, and in providing, with the requisite 
forethought, all the camp and cooking equipage, blankets, 
food, medicines, and the means of their convenient transport 
upon mules through a rough and mountainous country, of 
which large tracts were expected, and were in the end 
actually found to be, destitute (as a consequence of the 
earthquake) of either shelter or provisions. 

The remainder of the time was employed in making and 
recording observations and collecting information as to the 
phenomena of the earthquake, as it was felt in and around 
the city of Naples, and its immediate neighbourhood, and 
in seeking for evidence along the shores of the bay, from 
Pozzuoli to Castellamare, of recent change of level of the 
land, traceable to the shock. Arrangements were also 
provisionally made with an eminent French photographer at 
Naples for his following the probable track of the author, 
and obtaining a series of photographic views of such scenes 
and objects as might illustrate the results of the expe- 
dition ; and the author wrote home requesting the sanction 
of the Council of the Royal Society to his obtaining the 

B 2 



4 DIVISION OF THE WORK. 

photographs which now are referred to and inwoven with 
this Report. 

Before leaving the city of Naples, Professors Palmieri 
and Scacchi were consulted by the author, for any sug- 
gestions that they might deem desirable to make as to his 
examination, such as might occur to them firom their pro- 
longed familiarity with the seismic conditions of their 
country, and to be expected from their scientific eminence. 
He has to thank both for their cordial reception, and 
especially to record his obligations to Signer Guiscuardi, 
whose accurate and extensive scientific information and 
local knowledge were of great service to him in making 
his arrangements with the Government officials, and whose 
zealous kindness the author retains in lively remembrance. 

The following Report is divided into three principal 
parts. In the first, the questions proposed for obser- 
vation or solution are generally stated, and the methods 
of observation pursued in these earthquake regions to 
some extent indicated, with some remarks upon the phy- 
sical and other characteristics of the country itself, in 
relation to seismical effects. The second part embraces 
the narration of the observations actually made and infor- 
mation obtained, with some primary discussion of facts 
in a few instances. And in the third, the facts, so far as 
they admit of it, are classified and put together, and such 
conclusions or deductions drawn from them as they appear 
to the writer to warrant. 

In these the author will, for convenience and simplicity, 
write in the first person. 



PART I. 



CHAPTER I. 

OF THE QUESTIONS FOR INQUIRY, AND METHODS OF 
OBSERVATION, OF EARTHQUAKE PHENOMENA. 



Were Seismology an older and more mature branch of 
science than it is, it would be impertinent to enter at any 
length into the means and methods by which it is to be pur- 
sued, in the observation of earthquake phenomena. Dating, 
however, for anything approaching to scientific guidance 
or precision, not more than twelve years back,* it is the 
more necessary to make generally intelligible the methods 
of observation which can be pursued in a seismic region 
after the occurrence of the shock, in order that the evi- 
dence upon which conclusions may be drawn as to the 
direction, velocity, amount of movement, &c., of the latter 
may be accepted with their just weight ; and the rather, 
because as yet it is not to all persons quite self-evident 
how any information whatever can be had or conclusions 
drawn as to a phenomenon so perfectly transient and 
momentary as an earthquake shock, by examination, at a 
considerable time after its occurrence, of the region over 
which it has passed .f 

* This was written in 1858. 

f With the exception of the author's 'Instructions* in the *Ad- 
mii-alty Manual/ nothing whatever has been written bearing upon 



f5 MEANS OF INVP]STIGATION. 

An earthquake, like every other operation of natural 
forces, must be investigated by means of its phenomena 
or effects. Some of these are transient and momentary, 
and leave no trace after the shock, and such must either 
be observed at the time, or had from testimony. But 
others are more or less permanent, and, from the terrible 
handwriting of overturned towns and buildings, may be 
deciphered, more or less clearly, the conditions under 
which the forces that overthrew them acted, the velocity 
with which the ground beneath was moved, the extent 
of its oscillations, and ultimately the point, can be found 
in position and depth beneath the earth's surface, from 
which the original blow was delivered, which, propagated 
through the elastic materials of the mass above and around, 
constituted the shock. 

Again, certain effects, such as landslips, fissures, altera- 
tions of water-courses, &c., are produced of greater or less 
permanency affecting the natural features of the shaken 
country. 

The observation of each of these classes of effects bears 
reference to two distinct orders of seismic inquiry. 

By the first, we seek to obtain information as to the 
depth beneath the surface of our earth at which those 



sucli methods of observation. Mr. Hopkins, in his mathematical resume 
of the laws of elasticity, as bearing upon seismology, communicated to 
the British Association (17th Report, Oxford, 1847), incidentally points 
out the geometric conditions by which, if the emergence of a shock 
were known, the depth of the origin might be ascertained. The 
procedure generally had been previously suggested by the author in 
his original memoir on ' Dynamics of Earthquakes.' Trans. Roy. Irish 
Acad., vol. xxi., Part 1. The methods employed in this work are 
altogether distinct from that noticed by Mr. Hopkins. 



TWO ORDERS OF INQUIRY. 7 

forces (whether volcaDic or otherwise) are in action, whose 
throbbings are made known to us by the earthquake, 
and thus to make one great and reliable step towards a 
knowledge of the nature of these forces themselves ; and 
this is the great and hopeful aspect in which seismo- 
logy must be viewed and chiefly valued. It affords, if 
not the only, certainly, in the existing state of know- 
ledge, the best means by which we can entertain a well- 
founded expectation of ultimately obtaining clear and 
certain ideas as to the material and state of the internal 
mass of our planet, and comprehending the true nature and 
relations of volcanic energy. 

By the second order of inquiry we seek to determine 
the modifying and moulding power of earthquake upon 
the surface of our world as we now find it ; to trace its 
eflFects and estimate their power and extent upon man's 
habitation and upon himself. The first order of inquiry 
must be pursued by methods, chiefly mechanical, physical, 
or mathematical. The second by these, combined with the 
observational tact and largeness of a disciplined imagina- 
tion and eye that are amongst the accomplishments of the 
physical field-geologist Thus finally uniting our know- 
ledge derived from both directions, ultimately to form a 
clear conception of what is the function of the earthquake 
in the Cosmos, and to recognize the connection, fitness, 
order, and beauty, even of the volcano and the earthquake, 
as parts of the machinery of a wondrous and perfect 
creation. Like every aspect of nature, that we obtain 
with the more enlarged and undimmed eye of truth, it 
will prove to us that even here the great Author of all, 
is a God of order, not of confusion. 



8 QUESTIONS PROPOSED AND 

These, then, were the questions that I set before me. 
To endeavour to find the position, superficially and in 
depth of the centre of impulse of the shocks of the 16th 
December 1857, and to observe and discuss the effects of 
the earthquake, actual and prospective, upon the face of 
the country, in relation to all its physical conditions. 

The method of investigation which I purposed to adopt 
is based upon the very obvious truth, that the disturbances 
and dislocations of various solid objects by the shock of 
earthquake, if carefully observed with reference to their 
directions and extent of disturbance, and to the mechanical 
conditions in play, must afford the means of tracing back 
from these efi'ects, the directions, velocities, and other cir- 
cumstances of the movements or forces that caused them. 
This mode of examination, strange to say, appears to be 
perfectly new, and to have escaped the attention of all 
previous examiners of earthquake-shaken districts, as well 
as of all writers upon the subject. Thus the government 
reporters (for example) upon the great Calabriau earth- 
quake of 1783, or those more recently (Palmieri and 
Scacchi) upon that of Basilicata in 1851, seem to have 
been perfectly unconscious that in the fractured walls and 
overthrown objects scattered in all directions beneath their 
eyes, they had the most precious data for determining the 
velocities and directions of the shocks that produced them. 

The idea of applying number and measure to these 
never seems to have occurred to them. They merely 
describe the particular in a loose and general way, and 
only occasionally as curious, or remarkable, or inexplicable 
exemplars of the power of the disturbance. Hence they 
failed to draw a single conclusion of certaintv or scientific 



METHOD FOR SOLUTION. 

value as to the place whence the shock emanated, how 
deep this was under the earth, or in what direction it 
emerged from beneath it. 

As this method of seismic observation then, is novel, 
as I trust to show that it has proved fruitful in result, in 
this its very first application to nature ; and as, when fully- 
developed, it will be found a real *' Organon," a powerful 
machine for future discovery, I make no scruple in treat- 
ing at considerable length of its methods, in the hope that 
they may become understood, diffused, and applied by 
others. This method, I believe, will be hereafter recog- 
nized as one of the most fruitful applications yet made of 
mathematics to physical geology. 

Before leaving England for Naples, I communicated my 
views as to this method of investigation to my friend the 
Rev. Samuel Haughton, F.R.S., Professor of Geology, 
Trinity College, Dublin, and requested him to arrange for 
me a series of workable equations that should embrace 
most of the conditions as to direction and velocity of 
fractured or overthrown bodies that I expected to meet. 
With the utmost readiness, he applied his adroit and 
eminently practical mathematical powers to the task, and 
from him I received the equations given at pp. 125 et seq. — 
I. to XLV. — which formed some of the most valued work- 
ing tools of my deductions. 



CHAPTER IL 



ELASTIC WAVE OP SHOCK. 



The elastic or earth wave of shock, may reach a given 
point upon the surface, with any angle of emergence 
(the angle contained by the horizontal plane with the wave- 
path at the point of emergence), or in any azimuth. The 
path of the wave is a right line joining that point with 
the centre of impulse (or focus), the wave being assumed 
propagated thence in all directions outwards in spherical 
shells. This is strictly true only in an homogeneous elastic 
solid. 

Every point in a coseismal line (that in which such a 
wave shell simultaneously reaches the earth's surface) at 
the moment of shock describes a closed curve in space, re- 
turning to (or almost exactly to) the point from which it 
started into motion. The curve is one of double curvature, 
the vibration taking place nearly simultaneously, in three 
rectangular unequal axes. For the purposes of our inquiry 
we may neglect the transversal vibration, and may consider 
the closed curve of normal vibration as confined to vertical 
planes passing through the centre of impulse. In fact, 
the movement of the wave particles may be assumed as 
confined to right lines, indirectum with the path of the 



SEISMIC VERTICAL— ANGLE OF EMERGENCE. 11 

wave, whose length is equal to the amplitude of the wave 
or to one half of its complete vibration. 

As the coseismal curve (or crest of a wave of shock) 
enlarges its area, travelling outwards in all directions 
from the seismic vertical — that is, from the vertical line 
passing through the earth's surface (and centre) and the 
focus — every point in and upon the surface, in succession 
moves once forward and back in the direction of the wave- 
path, and to the extent of its amplitude at that point, or 
in two components, vertical and horizontal, that shall give 
such direction. 

We are not concerned here to consider the extent or the 
laws according to which the range of wave movement of 
each material particle, either in amplitude or attitude, or 
the velocity of its particles, vary with the distance from 
the focus. 

The angle of emergence for any given depth of focus 
diminishes as a function of the distance of any given point 
of the surface from the seismic vertical ; and I have shown 
elsewhere that the power of the shock to overthrow objects 
is, cceteris paribuSj a maximum at a determinate distance all 
round the seismic vertical; and this distance would be 
equal all round, were the earth homogeneous, and the focus 
or centre of impulse confined to a mathematical point. 
The centre of impulse in nature, however, occupies deter- 
minate, and often large dimensions. For this reason as well 
as from non-homogeneity amongst others, neither the 
meizoseismic curve (or that of maximum overthrow) nor 
the isoseismic curves (or those of equal overthrow) are 
found to be circles or even perfectly regular closed curves, 
nor concentric. 



12 VELOCITIES— OF TRANSIT— OF PARTICLE. 

For the same reason the observed angles of emergence 
will be found to vary from those that would be due to a 
focus of evanescent magnitude. 

The distinction must be clearly borne in mind between 
the velocity of transit of the wave —that with which the 
advancing form or seismal curve is transferred from point 
to point of the surface, and that of the earth particles 
moving within the limits of amplitude of each vibration. 
The former velocity is very great, nearly half as rapid as 
that of a cannon shot, and depends chiefly upon the elastic 
modulus of the earth's formations through which the wave 
transit is made ; but the latter, as now measured for the 
first time, is very small indeed, often not greater than that 
which a body acquires by falling from a height of two or 
three feet. 

It is, however, to the rapidity of transit velocity, or, which 
is the same thing, to the great rapidity with which the 
proper velocity of vibration of the wave passes, from to 
its maximum velocity, on reaching any material object, 
that the formidable dislocating effects of the very moderate 
maximum velocity of vibration arc due. We need not, 
however, here extend these preliminary remarks. 

The evidences fitted for observation after the shook, by 
which the conditions of earthquake motion are discoverable, 
may be divided into two great classes : — 

1st. Fractures or dislocations (chiefly in the masonry 
of buildings) which afford two principal sources 
and sorts of information. 

a. Information from the observed directions of 
fractures or fissures^ by which the wave-path^ 



EVIDENCES FOR OBSERVATION. 13 

and frequently the angle of emergence may be 
immediately inferred, 

b. Information from the preceding united with 

known conditions as to the strength of mate- 
rials to resist fracture^ by which the velocity 
of the fracturing impulse may be calculated. 

2ud. The overthrow, or the projection or both, of 
bodies, large or small, simple or complex. From 
these we are enabled to infer — 

c. By direct observation the direction in azimuth 

of the wave-path. 

d. By measurements of the horizontal and vertical 

distances of overthrow or of projection, to 
infer the velocity of projection and angle of 
emergence — both, or either. 

Fractures or dislocations present themselves always in 
directions more or less transverse to the wave-path. Over- 
throw or projection, on the contrary, always takes place in 
the line of the wave-path, or in the vertical plane passing 
through it ; but the direction of fall or of projection may be 
reverse (or in the contrary direction) to that of the wave 
transit, or it may be in the same direction with it. 

At the moment of the arrival of the earth wave at any 
object upon the surface, whose dimensions are less than the 
amplitude — an obelisk or pillar or single wall for example — 
motion is suddenly communicated to the body ; the velocity 
ol the vibrating particles rapidly increases from zero to its 
maximum velocity, and returns to zero, as it completes its 
first semiphase or half-vibration, the direction of move- 
ment in which is in the same sense as that of the wave transit. 



■f '^. 



14 NATURE OF OVERTHROW 

With nearly the same rapidity the velocity increases in 
the opposite direction from zero to the maximum, and 
back to zero again. The wave has then passed the given 
point, its whole phase or enlire vibration has been com- 
pleted, and it has produced its eflfects. The movement 
applied, is opposed by the inertia of the body moved, 
whose motions and final displacement depend upon the 
direction of the wave-path with regard to the centre of 
the body, its form, and the position of its base, or points 
of adherence or of support, and to the maximum velocity 
of the wave's proper motion. The applied velocity acts 
at the centre of gravity and in the direction of the wave- 
path, and the body, if free, apparently moves in the 
opposite direction to the vxtve in its first semiphase in con- 
sequence of its inertia. The force of displacement, with a 
given maximum velocity of vibration is therefore always 
proportionate to M, the ma&s, so that a heavy body, in 
the same shape and conditions is as easily upset as a 
light one. 

If the body be not free, if the line of wave transit pass- 
ing through its centre of gravity pass within the base or 
through any other support, it does not move in the first 
semiphase of the wave ; but if it be free in the opposite 
direction, it will be displaced in the second semiphase of 
the wave ; but as the wave movement is now reverse to 
that of its transit, the inertia of the body acting still con- 
trary to the applied velocity, now impels the body in the 
isame direction as the wave transit. 

In either case, and in either semiphase of the wave, the 
movement impressed, may be one of mere overthrow or 
upsetting, or it may be one of actual projection, or of both 



WITH RESISTANCE. 15 

combined, depending upon the special conditions of the 
body and its supports, &c. 

Where the body is projected from a base or support with 
which it has had friction or adherence, and that the line of 
wave transit through its centre of gravity does not also 
pass through the centre of adherence (that is, the point of 
the base, or between it and supports, in which all the 
resisting forces, of adherence, &c., may be supposed con- 
centrated), then, besides projection, a movement round 
a centre of spontaneous rotation within the body will also 
be impressed. Where this is due to adherence at the base, 
the rotation is generally in a vertical plane, and does not 
seriously disturb the plane of projection from that of the 
wave-path, i.e.^ of a vertical plane passing through the 
seismic focus and the body displaced ; but when also due 
to lateral adherence, or other still more complex condi- 
tions, the body is flung forward and whirls round on 
inclined axes, and finally comes to rest in some position 
quite abnormal to its original status, giving rise occasionally 
to complex phenomena from which nothing can be inferred. 
Where the body is large, such as a house or church of 
masonry, or even a single wall exposed to shock in the 
plane of its length, overthrow may be impossible with given 
dimensions and given angle of emergence of the wave ; but 
in such case dislocation or fissuring occurs, and the severed 
parts may or may not be overthrown, dependent upon the 
amount of the applied velocity consumed in producing 
fracture only. 

There may be no displacement whatever of loose objects, 
nor any dislocation of large masses, such as churches, &c., 
though exposed to violent shock, if its emergence be quite 



or very nearly vertical, and that the inaxiraam velocity of 
the wave does not exceed — 

H being equal X, the amplitude of the wave, the masses 
being in such case rapidly lifted up and let Ml again with- 
out the withdrawal of the support of the base. 

And generally, single objects situated upon the surfece 
of the earth, in firm and rigid connection with it, or so 
circumstanced that the line of wave transit through the 
centre of gravity passes through the surfaces of repose and 
of attachment, move with the earth itself, and are seldom 
disturbed as to their former position. Thus also, flexible 
objects, rooted trees, flag staffs, telegraph posts, and the like, 
are bent by the transverse forces impressed, but return to 
their positions, leaving only perhaps traces in the earth dis- 
turbed at their bases, of the direction of movement. 

A few examples may clear this part of the subject. In 
Fig. 1 let there be a large stone ball, adherent to a 
narrow base on top of its pedestal, which is fast in the 




ground, and exposed to a shock, the direction of wave 
motion of which, in the first semiphase, is from a to 6, and 
with velocity sufBcient to dislodge it. The ball, urged by 
inertia, and free to fall in any direction, will be projected 
in i to o, contrary to the wave, and describing a trajectory 



r EXTRANEOUS SUPPORT. . 17 

in the plane of the wave-path, will fall to c, and if its 
velocity in the horizontal axis be not wholly destroyed (as 
by falling on soft ground), it may roll, and so cease to give 
any indication of subsequent value. We are not now con- 
cerned with what is the trajectory, or with its modify- 
ing conditions. It is obvious that these might be such 
that the ball shall drop, nearly plumb to the ground, 
but always in a direction contrary to that of the wave 
transit. 

K a similar ball however, and exposed to a like shock, 
have a support — such as a wall, for example, at the side a 
(Fig. 2), which is not overthrown by the shock, but carried 
along with the wave in the forward movement of its first 
semiphase — then the ball, although pressed by inertia 
against the adjacent face of the wall, is prevented falling in 
that direction. It also, therefore, has impressed upon it, 
the maximum velocity of the wave in its first semiphase. 
When, therefore, the wave itself arrives at its maximum 
velocity in the contrary direction — viz., in its second semi- 
phase — the ball, by its inertia of motion impressed in the 
previous semiphase, is then thrown in the same direction as 
the wave transit a to 6, and projected to the ground at rf, 
as before. 

It might happen that the wall might be so related in 
dimensions, &c., to the velocity and direction of the wave, 
that it should remain standing long enough to produce the 
effects described upon the ball, but should immediately 
afterwards begin to fall, fracturing and turning over upon 
the point / in a direction contrary to that of the wave 
transit ; and in such a case there might remain no evidence 
to show, fi'om either the ball or the wall, in which direction 

VOL. I. c 



18 



. SEISMIC VERTICAL—EMERGENCE. 



the wave transit was made, whether from a to 6 or the con- 
trary. We might ascertain the path of the wave, or rather 
the azimuth in which it lay, but no more. 

If at two distant localities we can obtain even that much 
information, we can assign the place of the seismic vertical. 
For if (Fig. 3) by one shock the ball b be projected in the 
wave-path a' to b\ in either direction, suppose contrary to 
the wave transit, and also the ball a at a distant place not 
in the same right line, also projected, say either as the 





Fig. 3. 



Fig. 4. 



Fig. 5. 



former or in the same direction as the wave transit a to 6, 
then we obtain two azimuths, which can have but one 
point of intersection in o, which is that through which the 
seismic vertical passes. 

Where the body projected (Fig. 4) is circumstanced so 
as to retain the position in which it alighted upon the 
ground, so that we can measure the vertical and horizontal 
axes 6 c, 6 c?, then knowing the maximum velocity of the 
wave, and which is equal that of projection, we can find 
the angle of emergence in the, plane of projection whose 
azimuth is observed, and vice versd. 

And if wc have two closely adjacent objects projected in 
the same locality, and the above conditions observed, we 
can calculate both the angle of emergence and the velocity. 



OSCILLATION. 19 

It will most generally happen that a regular solid (such 
as an obelisk, &c.) will fall prostrate whenever the maxi- 
mum velocity of the wave is such as to produce in it 
oscillation sufficient to destroy statical equilibrium ; and as 
the arc of oscillation due to a given velocity may be 
assigned, if we know the angle of emergence of the wave, 
80 as to arrive at its horizontal component of velocity, we 
can always assign an inferior limit to the maximum ve- 
locity of the wave that overthrew the object whose di- 
mensions, &c., we have observed. And if any other 
regular solid, although dissimilar in form, can be found at 
the same locality, which has not been overthrown, we 
may obtain from it a superior limit of such velocity. 

It is possible, however, that oscillation may occur to the 
limit of equilibrium, or even somewhat beyond it, without 
involving the fall of the body ; for the relation may possibly 
be such between the time of oscillation of the body (Fig. 5) 
upon one of its edges or arrises /, and the time of a com- 
plete phase of the wave, that the equilibrium may be 
restored by the movement impressed in the second semi- 
phase of the wave in the contrary direction to that first 
communicated, and before the body has had time to fall 
over, beyond the limit of such restoration ; the adherence or 
Mction of the arris /, with the base, producing the neces- 
sary hold, by which the wave so acts upon the body during 
its second semiphase, in the direction a! to //. 

If this be sufficient to bring back the centre of gravity 
through the horizontal distance between the verticals 
c and / during the time of the second semiphase of the 
wave, the body does not fall, but on the cessation of earth 
movement, topples back to its original position of perpen- 

2 



20 EFFECTS OF FORM 

dicularity, overpasses it, and after a succession of decreas- 
ing oscillations remains vertical as at first. 

In so resuming a position of rest, it may be so circum- 
stanced as to the nature of its base and arrises of oscilla- 
tion, as to twist considerably from its first position, round 
one or more vertical axes. 

This is a condition of things that very rarely occurs, except 
with small objects, like vases, statues, or pinnacles consisting 
of a single block. There are few masses actually found suflS- 
ciently hard, when of large size, to prevent the arris / splin- 
tering or crushing at the first movement to such an extent as 
to destroy all chance of restoration of position, even if the 
mass held together as one block ; but in walls, towers, cam- 
paniles, or other compound masses, made up of blocks more 
orless firmly united, dislocation at several points takes place 
from the outset. Such masses being more or less flexible 
and elastic, bend first, break at the moment of maximum 
velocity of the wave, and then topple over piecemeal. 

With the same velocity of wave, very different effects are 
produced, with regard to overthrow as the angle of emer- 
gence varies, and as the form of the body is different. Thus 
(Figs. 6 and 7), in the first, the wave emergent in the 




Fig. 6. Fig. 7. 



direction a to 6, through the centre of gravity produces no 
disturbance of position in the "boulder stone," the ex- 
treme point s of the bed preventing rotation in the first 
semiphase of the wave, by a force measured by d c, and the 



IN REGULAR BODIES. 



21 



point / in the second semiphase by a force measured 
hjef. 

In feet, no velocity of earth wave occurring in nature, 
even with the emergent angle ^ = 0, i. e.^ horizontally, 
could overturn a block proportioned as in Fig. 6. If 
resting on a bed of earth or stone, it might slide and 
plough along upon it, and knowing certain coefficients, 
the length and dimensions of the channel or course cut 
by it would enable the wave velocity to be arrived 
at. In the case of the other block (Fig. 7), however, 
it would be overturned by a wave emergent in the 
direction a to 5 in either semiphase of the wave, the 
forces of overthrow in each being proportionate io dc and 
ef. So in more regular solids, the column shaft (Fig. 8) 
may be overturned by a sufficient velocity of wave, in either 
semiphase, emergent at any angle between h e, passing 
through the centre of gravity and the horizontal wave- 





Pig. 8. Fig- 9- 

path passing through the same, the overthrowing force, 
with a given emergence and direction of wave-path, a to 6, 
being proportionate to c d in the first semiphase and to ef 
in the second. 

But the pedestal or "cippus " (Fig. 9) can only be 
overturned in the second semiphase of the wave, however 
great its velocity, if emergent in the direction a to &, nor 



22 PROBLEMS RESOLVE 

then unless with a very great velocity, the efifect of the 
wave in its first semiphase, however great its velocity, 
being merely to urge the whole solid against the ground 
in the direction 6 to a ; and if it stand free upon a surface 
with friction (as an article of furniture, a cabinet or press, 
for example), to cause it to slide in the direction n to m 
horizontally. 

The initial velocity of a body projected by earthquake 
shock, or that of some point of one overturned, is equal to the 
lYiaximum velocity of the earth wave ; for upon the prin- 
ciple of the equality of action and reaction, the greatest effect 
produced must be due to the greatest applied velocity. 

And so also of fractures ; they are to be considered as 
due to a force M x V, M being the mass of the frag- 
ment broken off, and V the velocity of its centre of 
gravity or of oscillation, and equal to the maximum ve- 
locity of the wave, at the instant of its passing through 
which, fracture occurs. 

It will thus be apparent that the principal phenomena 
presented by the effects of earthquake shock upon the 
objects usually occurring upon the surface of the inhabited 
parts of the earth, resolve themselves into problems of three 
classes, and are all amenable to mechanical treatment, viz. — 

1st. Problems relating to the directions and amount of 
velocities producing fracture or fissures. 

2nd. Problems relating to the single or multiplied 
oscillations of bodies considered as compound 
pendulums. 

3rd. Problems referable to the theory of projectiles ; 

in which last, as the velocity is small, and the mass usually 



INTO THREE CLASSES. 23 

great in proportion to the range, which is also small, we 
are not disturbed by any consideration of resistance from 
the atmosphere, ^ 

These three classes of problems frequently are found 
combined in a single example — thus fracture and over- 
throw often occur together, or fracture and projection, and 
sometimes all thiiee are united ; a body (a gate pier for 
example) being broken ofif at its base, and overturned, but 
with a velocity more than sufficient for both, so that it is 
also projected, or thrown to a certain distance from its 
base. Although a less regular arrangement, it will tend 
to greater clearness, now to leave the further strict me- 
chanical consideration of these questions, with the pre- 
liminary statements that have been made, and proceed 
first to describe pretty fully, the characteristics and details 
of structure of the buildings, &c., to which those prin- 
ciples will be applied in the present Report ; and then to 
enter minutely upon the nature, of the fractures or fissures 
produced by earthquake shock in such buildings, &c., and 
describe the methods and conditions of observing them, and 
afterwards treating the observations; and finally to give 
in a connected form the equations referring to the treat- 
ment of all the classes of problems, as respects velocity, or 
direction obtained by calculation from velocity. 

Almost all that follows with reference to the observation 
of the directions of fissures (or fractures), therefore is to be 
viewed as descriptive of the methods of arriving at direction 
only of wave-path, without reference to the velocity of the 
wave particles, or to any other mechanical conditions 
except those which determine the directions of such fis- 
sures as observed in buildings, velocity being determined, 



24 OBSERTATIONS AVAILABLE. 

and cUao emergeneej indirectlT, by calculation applied to 
the observed conditi(His of the forces employed in pro- 
ducing fractnre, overthrow, <wr projection. 

FL^sures in buildings, not overthrown, are, in fiwjt, the 
sheet anchor, as respects direction of wave-path to the 
seismologist in the field. 

The observations nsnallv available, npon single or iso- 
lated objects, such as pillars, obelisks, vases, or statues 
overthrown, or others often of small size though com- 
paratively rarer, are generally not less important, as 
determining direction, than those to be made upon objects 
of united or complex construction, or however large, such 
as buildings of various sorts. The latter are, however, the 
staple indices upon the careful observation of the injuries 
to which, we are mainly dependent for arriving at the 
directions in azimuth of shock. 



CHAPTER III. 

CONDITIONS OF EARTHQUAKE ACTION UPON ARCHITEC- 
TURAL STRUCTURES. 



The eflfects produced by precisely the same shock, acting 
upon buildings differing in position, construction, material, 
&c., are so great, that it will be necessary to treat some- 
what in detail of the conditions of earthquake action upon 
architectural structures ; for without a thorough under- 
standing of these, one is almost certain to be led astray by 
the strange, and often, at first sight, perplexing phenomena 
of destruction observable. 

Throughout the kingdom of Naples, the edifices of 
cities, towns, and rural places present very uniform and 
striking characteristics, though varying much in dignity 
and size, &c. 

In a few of the largest provincial cities, such as Potenza, 
Melfi, (No. 10, Coll. Roy. Soc.,) &c., the buildings, more 
especially those of government, the ecclesiastics, and the 
great landowners, present more or less of the majestic 
size, and architectural style, of the city of Naples itself. 
Loftiness, thickness of walls, apertures few but large, 
square-headed windows, and arched doors and gateways, 
with heavy tiled roofs, of low pitch, and with deeply over- 
hanging eaves characterize the outside. The style of archi- 
tecture, when style is attempted, is generally Roman, with 



26 STRUCTURE OF BUILDINGS 

cinque cento, or a still later and more debased style of 
ornamentation. The usually grandiose effect, however, 
very generally conceals, building workmanship of a very 
inferior quality. 

The building materials of the kingdom generally, are 
lavas and tufa in the volcanic districts, limestone of 
various qualities, and brick (these are by far the most 
prevalent) ; and, in their respective localities, some sand- 
stones, slaty rocks, and very rarely those from the ancient 
igneous rocks. 

Limestone and brick are the staple materials of the 
regions to which this Report principally refers, except 
those of Naples and Melfi. The limestone is very seldom 
found, either in the Jurassic or cretaceous formations, well 
bedded, or capable of being raised in long flat blocks. 
Lime is abundant, but the mortar often of very slender 
cohesion, from too great a proportion of lime and the want 
of a proper quality of sharp sand. Hence the general style 
of construction of wall, even in first-class buildings, consists 
of a coarse, short-bedded, ill-laid rubble masonry, with 
great thickness of mortar joints, very thick walls, without 
any attention to thorough bonding whatever. The opes of 
windows and doors often have cut limestone jambs, lintels, 
and dressings, which are but ill connected with the rest of 
the walls. In general, the external faces of the walls are 
concealed by plaster or rough cast. This is even the usual 
style of building for the better class of churches and 
monasteries. It has prevailed from a remote period, and a 
fair average illustrntion of its appearance is seen in the 
west end of the Villa Carusso near Auletta (No. 11, Coll. 
Roy. Soc). 



OF SOUTHERN ITALY. 27 

The floors in the better sort of town houses and palazzi, 
are formed of joists of fir timber, very commonly round 
as it grew, from 6 to 9 inches in diameter, placed at about 
3 feet apart. The ends are inserted some inches into the 
walls, but are neither bedded on, nor connected by, any 
"tossils" or bond timbers, none of which are ever placed 
in the walls. Upon these joists a planking of fir, oak, or 
chestnut, from an inch to an inch and a half thick, is laid, 
rough as it comes from the saw, and pegged or spiked to 
the beams, and upon it a bed of concrete or beton, com- 
posed of lime, mortar, and broken tufa, brick, or stone is 
laid, to 6 to 8 inches in depth, and the surface of the latter 
is laid with red tiles — square or hexagonal — or sometimes 
plastered over with puzzolano mortar, and painted in oil. 

The under surface of the floor is often bare, and the 
joists visible ; in other cases a plastered ceiling is secured, 
by heavy lathing, up to the joists. See Photog. No. 12 
at St. Pietro (CoU. Eoy. Soc.) 

A floor of this sort weighs from 60 to 100 lbs. to the 
superficial foot. Floors of palazzi, are also not unusually 
formed of arches and groins, built of hollow pottery em- 
bedded in mortar, the haunches filled in with beton, and 
plastered soflFeits, with tiled surfaces to the floors, which, 
thus constructed, are of still greater weight. 

The roofing also usually consists of round fir timber. 
The framing is of the simplest character except in some 
church and other roofs of great span, when the timber is 
squared. It consists commonly of principal rafters at 
3 to 5 feet apart, connected by a rude collar brace, of 
round fir also, trenailed or bolted to the rafters. The feet 
of the rafters sometimes rest upon a wall plate of squared 



28 GENERAL APPEARANCE OF 

or of half-round timber, but often bed directly on top of 
the wall. These principals are crossed by stout sawed 
laths, and upon these are laid the common heavy ridge and 
furrow tiles, whose appearance is so familiarly character- 
istic of Italy, and so much more picturesque, than construc- 
tively good. These tiles are from | to li inch thick, 
each course from 18 to 24 inches long, and they are fre- 
quently laid dry, and not secured down in any way but by 
their own great weight, except at the ridges, where the 
ridge tiles are cemented down in mortar. Roofing of this 
character weighs very little less than an equal surface of 
the flooring just described. 

Framed roofing of large span and squared timber is 
not common in churches, &c., which are usually vaulted 
with brick or stone, dome'd or groined. 

It will thus be remarked that in the construction of the 
more important buildings, the mass and inertia, of walls, 
floors, and roofs are enormous, while the bond and con- 
nection of each of these, and of all to the others, is loose 
and imperfect. 

It is in the mediaeval towns and villages of the interior 
provinces, however, that these conditions are still more 
evident. Nothing can be more striking than the general 
appearance of these ancient abodes. They are almost 
without exception perched upon the summits and steep 
flanks of precipitous *' coUines," usually rounded conoidal 
hills of limestone, sometimes abrupt and rocky elevations, 
whose slopes and shelves are occupied and their craggy 
heights crowned by the houses, built out to the very 
edge of the precipice, with no windows or doors looking 
outwards, or, if any, high up and inaccessible to any 



THE ANCIENT TOWNS. 29 

whe should climb the rock. Seen from beneath, in the 
valley bottom, through the keen bright air, and relieved 
against the sky, these old towns seem as though we 
could reach their interior in half an hour's scramble ; yet 
often three hours' painful toil upon our mule will but 
suffice to bring us — by long traverses over rough and 
rolling stones, and by an approach road that is often the 
bed of a torrent in time of rain — to the ancient gateway, or 
to the narrow and obstructed street entrance by which 
alone we can penetrate the interior. Everything about 
these places is characteristic of their origin, its remoteness, 
and of the savage manners and times in which they were 
founded. 

The irregular and narrow streets, not more than from 
5 to 12 or 15 feet wide, are steep as staircases, until we 
reach the very summit of the town, where the little " piazza " 
and the principal church, or some gloomy-looking monastic 
pile, mostly form its centre and heart. We pass along 
between houses of all heights and sizes, beetle browed, and 
with low arched ^^ portone," and small, unglazed, and often 
sashless windows, few, and high up. The unpaved and 
unformed surface, often the bare rock worn into steps, of 
these wretched streets, is the common receptacle of the 
filth of every house ,* pigs at all times, and often goats 
at night, make them their common resting-ground. There 
is neither sewerage nor water supply, and in winter 
wet, we wade through ordure ankle deep. Castelluccio 
(see Photog. 13) is a good illustration of the site 
and exterior of many of these towns. They all still 
retain the impress, of the semi-oriental character of the 
early settlers of Magna Graecia, of the savage violence 



30 SITES AND POSITIONS OP 

and tyranny, of Saracen and Lombard conquerors, of 
middle-age superstitions and barbarism, and of a people 
condemned for ages, by misgovernment to an unprogressive 
state of ignorance and poverty, in the midst of the richest 
bounties of nature. 

The towns owe their elevated position, primarily beyond 
doubt, to the necessity for defence and security in ancient 
times; but an universal belief exists that this elevation 
secures them against malaria, as it certainly relieves them 
in the summer from the unbearable reflected heat and pent- 
up air of the valley bottoms. These advantages, however, 
seem dearly purchased at the cost of difficult accessibility, 
even were proper road approaches made to them. 

No roads whatever, suited to wheel traffic, exist through- 
out the kingdom, except the five great military ways, and 
these are perfectly unconnected by branches, with any but 
a few great towns : hence all produce has to be carried by 
mules, or by hand ; and journeying oflF the military road 
can only be accomplished in the same way, or on foot. 

It results from the perched positions, of almost all these 
towns that they are exposed to the severest effects of every 
earthquake shock. They are rocked as on the tops of 
masts. Padula is a good example of the larger and less 
ancient class of these towns (Photog. 14). 

The style of building in these provincial towns, is much 
the same as has been already described of the cities, but 
poorer and humbler. The houses are seldom under two 
stories, rarely exceed three. The huts of the poorest 
classes (the land labourers, and shepherds) are but one 
story, huddled together in utter confusion ; and the chief 
difference in point of masonry, in these country towns 



THE PROVINCIAL TOWNS. 31 

from that described is, that sur&ce limestone — or that 
taken from the naturally exposed beds of rock — is com- 
monly used to save labour in obtaining better, and hence 
the walls built abnost invariably, of this coarse " nobbly " 
rubble, in half-rounded blocks, or rather lumps of stone, 
of neariy equal length, breadth, and thickness, and resem- 
bling nothing in form more than irregular loaves of bread, 
are almost devoid of masonry bond, and are shaken dqwn 
into a heap, by a shock that would only fissure a well-built 
and properly bonded structure. 

It results, too, from the extreme steepness of the scarps 
and terraces upon which these poor edifices are placed, 
that when some are shaken down they fall against and upon 
those that are beneath them, and increase thus the common 
ruin. This took place with dreadfiil elTect at Saponara 
and elsewhere in the shock of 16th December, 1857. 

The hill sites of these provincial towns are found most 
commonly on the summits and flanks of the lower spurs of 
hills that skirt the great mountain ranges, and are on the 
confines of the " piani," or great valley plains or slopes, 
that separate the chains ; but sometimes they are absolutely 
upon lofty mountain tops (Conturso, Montesano), or at 
the edges of steep ravines (Bella) ; or on spurs high up on 
mountain flanks, as Petina, on the flank of La Scorza. 
Occasionally they stand (or stood) upon the flat tops, of 
insulated and enormously deep masses, of loose alluvium 
and clay, like Montemurro and Sarconi, with large rivers or 
torrents running at the bases of the clay cliffs, and eating 
them away. 

This is almost universally the case in the great piano of 
Calabria Ulteriore Primo, and hence the expression of 



32 FURTHER REMARKS, ETC. 

Dolomieu, as to the destruction of the towns there in the 
great shock of 1783, that "the ground was shaken down 
like ashes, or sand laid upon a table." 

Further remarks as to the situation of these towns, how- 
ever, will best be made when observing upon some of the 
great physical features of the earthquake region, and of 
Naples generally. 

With these remarks as to the general character of the 
buildings we have to deal with, I now proceed to the con- 
sideration in detail of the effects of earthquake upon them, 
and the phenomena presented by fractures and fissures in 
their walls, floors, &c. &c. 



CHAPTER IV. 

FIRST CLASS OP DETERMINANTS — FRACTURES IN RECTAN- 
GULAR BUILDINGS AS EVIDENCES OP WAVE-PATH. 



If an isolated wall (a parallelepiped) of masonry or brick, 
founded on level ground, be subjected to the transit of 
an earth wave, whose velocity is suflBcient to affect the 
continuity of its parts, the resulting fractures will vary 
with the direction of the wave-path as respects the plane of 
the wall, and with the angle of emergence of the wave. 

1st. If the wave-path be horizontal, or nearly so, and in 
the plan of the vxill^ tlie earth moving forward beneath the 
wall, tends to carry it forward by the grasp of its foun- 
dation and at its own velocity ; but this is opposed by 
the wall's inertia. The material of the wall being, within 
narrow limits flexible and elastic, the tendency is to distort 
its figure, thus. The wave reaching the end a (Fig. 14 his\ 
first, with a transit from a towards 
A, the end a first begins to as- 
sume the form e a, rapidly taken 
by the whole wall, if sufficiently ^ Fig.^Twj. 
high in relation to its length. The wave traverses be- 
neath the whole length, the materials, in virtue of their 
elasticity, oscillate in the same direction between e and / 
throughout the whole mass, and if the wall be fissured, 

VOL. I. D 




34 PATH IN REFERENCE TO BUILDING 

it will be by a nearly vertical crack, widest open at top, 
and extending more or less down towards the base. If 
the wall were of absolutely uniform cohesion, there would 
be two such fissures near either end, or only one in the 
mid length, dependent upon the density, cohesion, and rate 
of force transmission of its materials, and the velocity of 
the wave movement: practically, such a wall is usually 
fissured in the weakest place. 

2nd. If the wave transit be horizontal, or nearly so, and 
oblique to the plane of tlie wall^ the latter either falls pros- 
trate wholly, or a triangular fragment is thrown off from 
the end last reached by the wave, and in the direction 
contrary to its transit, or the wall is fissured, as in the 
first case only, dependent chiefly upon the greater or less 
obliquity of the line of transit to the plane of the wall. 

Isolated walls, exposed to oblique or to directly trans- 
verse action, thus when tolerably thick, may sometimes be 
twisted considerably out of plumb without losing equili- 
brium or complete cohesion. 

3rd. If the wave emerge with a steep angle to the horizon^ 
the distortion is that of compression in the diagonal of the 
wall's plane, nearest parallel to the line of wave transit; 
and the fissures, if they occur, are also diagonal to the 
horizon, and approximate to directions perpendicular to 
the lines of pressure, i. e.^ to the line of wave transit. 

If the velocity of the wave be sufiBcient, in relation to 
the density and cohesion of the wall, a triangular mass 
may be projected from the end at which the wave passes 
out from it. 

Reference will frequently occur to the directions in azi- 
muth and emergence of the earth wave, relative to those 



NOMENCLATURE. 35 

of walls, buildings, or other objects affected by it. It will 
be convenient, therefore, to fix a nomenclature for these 
relations. A rectangular building, two of whose walls run 
north and south, and the other two east and west, may be 
called a cardinal building : buildings whose four walls run 
in any other azimuths will be described as ordinal. 

Referring generally to the direction of wave transit in 
its horizontal component, or when nearly horizontal, as 
aflfecting cardinal buildings (which alone are generally 
suited for observation), it will be denominated normal 
lichen its azimuth is parallel to either pair of walls, viz., 
either north and south, or east and west. 

When the line of wave transit, or its horizontal com- 
ponent, are in some intermediate azimuth, it will be said to 
be abnormal. 

When a normal wave is an emergent one (the line of 
transit, or wave-path, inclined to the horizon) it will be 
called a subnormal wave ; and in a similar case the abnormal 
wave will be designated as subabnormal. 

These expressions will save much prolixity. 

When the observer first enters upon one of those earth- 
quake-shaken towns, he finds himself in the midst of utter 
confusion. The eye is bewildered by " a city become an 
heap/' He wanders over masses of dislocated stone and 
mortar, with timbers half buried, prostrate, or standing 
stark up against the light, and is appalled by spectacles 
of desolation (such as those in Photogs. Nos. 15, 16, 17, 
18, 19, and 20, Coll. Roy. Soc). 

At first sight, and even after cursory eja^minatiou, all 

» 

appears confusion. Houses seem to have been precipitated 
to the ground in every direction of azimuth. There seems 

D 2 



36 FIRST SIGHT OF RUINED CITIES. 

no governing law, nor any indication of a prevailing direc- 
tion of overturning force. It is only by first gaining some 
commanding point, whence a general view over the whole 
field of ruin can be had, and observing its places of greatest 
and least destruction, and then by patient examination, 
compass in hand, of many details of overthrow, house by 
house and street by street, analyzing each detail and com- 
paring the results, as to the direction of force, that must 
have produced each particular fall, with those previously 
observed and compared, that we at length perceive, once 
for all, that this apparent confusion is but superficial. 

We discover the cause, and in doing so obtain the key 
to all future correct and ready detection of the general 
directions of shock, by having learned to choose the proper 
class of buildings for our observations. 

We find that wherever the ruin is complete and feature- 
less — defying deduction —there the streets have been nar- 
rowed to five or twelve feet wide, have run winding hither 
and thither, ascending and descending, and that the walls 
of the houses, following their irregularities, have stood in 
every possible azimuth ; that the exposed fronts and sides 
of the houses have faced every point of the compass ; and 
often that the confusion produced by the shock thus 
reaching walls at the same moment at every conceivable 
angle, has been further increased by the Mling houses 
having staggered against each other, and so some that 
might if alone have fallen in other ways, or might have 
escaped with only fissures, have been beaten to the earth 
by their neighbours. This sort of destruction, too, we will 
have remarked, belongs to the poorest habitations and 
worst built and densest parts of the town, where the 



BUILDINGS FOR OBSERVATION. 37 

wretched rubble masonry falls incoherent at the slightest 
jar. 

We advance then to the churches, the barracks, or cas- 
tello, the monasteries, the Casa Communale — to any of the 
better built and isolated^ or nearly isolated buildings, and 
we soon discover that amongst these there are some that 
in every place present certain grand characteristics of par- 
tial or complete overthrow, and that these are everywhere 
generically much alike. 

These we observe, aided by the prismatic compass, and 
with our previous dynamic knowledge, and soon discover 
that wherever such buildings, and not very dissimilar to 
each other, have been placed under like conditions, and so 
that their walls are in the same azimuths, like dislocations 
have aflfected them, and that where the directions in which 
the forces that we know must have produced the observed 
dislocations have not passed very diagonally through the 
walls, they have produced eCFects, regular and accordant 
with each other, and from which the directions may be 
inferred in which the forces themselves acted. 

After a little experience we discover, that in every town 
(and frequently in other places) we may find rectangular 
buildings whose walls run very nearly north and south 
and east and west, and that these respond to our questions 
best ; and finally, that buildings so posited, and having 
certain necessary characters of structure, when not too com- 
pletely destroyed or overthrown, will enable us to discover 
the direction of wave transit, whatever may have been its 
line with reference to the walls. 

It remains to describe, therefore, the effects produced 
upon such cardinal buildings by earthquake shock, to trace 



CARDCCAL BCILD[SGS ASD 



ftom the effects their causes — from the dislocations the 
forces that {undnced them aod their directions, and to 
point oat SfMne of the more impixtant modifications of etkcx 
dne to differences of masooiy, o( fonn, of architectore, of 
wall apertures, and other such accidental couditkHis. 

Commencing with the ^m{rfest case. If a cardinal 
bnUdmg consisting merely of foor annx^d vails be ex- 
posed to a normal fhock, capable of fisoring the masotuy, 
bnt not completely overthrowing it, the fisnres will be 
foand as oearlr vertical cracks following the joints of the 
masonry, and within a few leet {mote or less) of each 
quoin, as in Figs. 21-23, and Figs. 22-24, in plan. 

Rg- SI. ng. 21 




Pig. 2*. 



The fissnres being widest at top, and becoming a scarce 
visible line at part of the way down the walls, or perhaps 
extending to their base, the earth wave, if in the direction 
a Ui h, reaches the end wall, a, first. Its inertia acts as an 
c^ioal and opposite force at its centre of gravity, and 
t<;n(]» U} cause it to be left behind while the remainder 
of the building is pushed forward. The end wall totmrds 
the direction /r(nn which the shock has come moves in the 



NORMAL SHOCK. 39 

opposite one, and if fracture occur the side walls fissure a 
short way off from the quoins, and the movement of the 
end wall is one of rotation round some horizontal line or 
lines situated along the length of its base. 

Were every part of the walls of the building of perfectly 
equal cohei^ence, and the mte of wave transit the same in 
its materials as that of the earth wave, the fracture would 
occur exactly at the internal angle of the wall at each 
quoin, breaking the side walls, across in a plane coinciding 
with that of the internal face of the end wall. But the 
quoins are in practice built with larger, longer bedded, and 
better dressed masonry than the rest of the structure ; and 
hence from this cause alone, without reference to others, the 
fissures are removed along the side walls nearer the 
middle, and into the less coherent masonry of the walls, 
and take place at c. 

The earth wave pushes the side walls along with it, and 
these push the end wall h at either quoin before them. 
The end wall 6 therefore cannot fall by inertia in the same 
way as that, a, being propped up by the side walls. The 
earth wave, however, having passed its first semiphase, 
returns through the second half vibration in the opposite 
direction, and, we may assume, with equal velocity. The 
same set of forces now operate upon the end wall, 6, the 
movement of the whole mass being in the direction b to a, 
and as described for the former end wall ; so that b tends 
to turn over upon its base in the contrary direction to the 
movement of the wave itself in its second semiphase, and 
the side walls are fissured as before at a distance from the 
quoins greater or less along them, as at e (Fig. 21). As 
the force producing fracture and dislocation at any given 



40 WIDTHS OF FISSURES 

velocity is always proportionate to M — the mass broken 
oflF or dislodged — so the extent of dislodgement after frac- 
ture (the materials being the same) is always propor- 
tionate to the velocity; and hence in any one building 
of like material and masonry the width of each fissure is 
proportionate to the velocity that has been effective in 
opening it ; and we may compare component velocities in 
the directions of the planes of parallel or abutting walls 
by means of the widths of sijch fissures, the width in every 
case being measured with reference to an unit in length 
of the fissure from its origin, or where it becomes evanes- 
cent. This unit length may be arbitrary, but 10 feet 
in length of fissure is a very convenient unit, and the 
widths expressed in inches and decimals for that unit. 

It is almost invariably found that in every building 
(with certain exceptions, to be noticed), although the 
masonry and form, &c., of the building may be quite or 
very nearly alike at both ends, the fissures c and e, do 
not occur at equal distances from the respective quoins 
(measured along the side walls), nor are they equally 
opened, large, and long, at both the opposite ends. 

Whether this arises — as, from other considerations 
respecting the vibration of pendulous lamps set in motion 
by shock, and to be hereafter noticed (Part III.), seems 
probable — from a real diflference in velocity in the two 
semiphases of the wave itself, and that the second semi- 
phase is described with a somewhat slower velocity than 
the first, owing to defect of perfect elasticity in material 
substances composing the earth's surface — or whether it is 
due to the conjoint action of the elastic wave (the earth 
wave) itself, and of the wave of elastic compression of the 



AND DEDUCTION— MASKING CIRCUMSTANCES. 41 

materials of the walls themselves— or to whatever other 
cause, which future research must make clear, the fact may- 
be accepted as certain and very general — that the end 
wall which is first acted upon by the wave (whenever it is 
something near normal), has the higher velocity shown 
upon it, and that the fissures at that end are, cceteris paribus^ 
found to be wider than those at the opposite one. 

The fissure formed at the end a, that first reached, is 
frequently rather wider than what is precisely due to this 
difference in velocity in the two semiphases of the wave ; for 
the end a is first fissured, the end h is next fissured by the 
second semiphase, which leaves the end wall b broken off, 
behind it, but carries back with it both side walls in the 
direction of its own return motion, and towards the end 
wall a. But more or less dust and broken fragments are 
often intercepted in the fissure a when first opened. 
These hinder the mass broken oflF at a from approaching 
the side walls, and closing the fissures (by the inertia of the 
broken-ofif mass), so that the side walls, in this return 
movement, push the end wall a before them, through the 
intervention of these obstacles, and so a second movement 
is impressed (small in extent) upon the broken-off end a, 
in the contrary direction to the wave transit, and in the 
same direction with its first movement, which ends by 
increasing the final width of the fissures at the end a. 

The chief disturbing causes that interfere with and mask 
:he regularity of this phenomenon are — The wave being 
subnormal and emergent at a considerable angle ; in which 
3ase the length of the dynamic couple (as has been already 
generally explained) that measures the overthrowing and 
iislocating power at a given velocity, is greatest in the 



42 DEDUCTION AS TO ORIGIN. 

second semiphase of the wave, and to such an extent, as to 
obliterate the effect of the difference in velocity of the two 
semiphases, and either leave the fissures equal at both 
ends, or even make those at the end h the wider. 

Inequalities in the materials or masonry at the opposite 
ends in the line of the wave-path — want of complete or 
nearly approximate symmetry in the size and form of 
those ends— perforations of doors or windows, or such- 
like sudden changes of continuity of wall — and great length 
of bond in the wall stones at all or at a few points — are 
the other conditions which chiefly perplex and interfere 
with the phenomenon. 

Practically, however, this feet is a guide of much im- 
portance in seismic observation, inasmuch as it enables 
us very frequently to decide, with more or less certainty, 
as to the direction of wave transit, from conditions that 
otherwise would afford no information beyond that of the 
path of the wave, leaving it quite uncertain whether the 
seismic vertical were to be sought for towards a or 
towards b. 

Where the phenomena are clear, we may, on the con- 
trary, always conclude that it lies along the wave-path, 
towards the end that presents the widest fissures. Very few 
large and massive cardinal buildings will be found that 
will not give, as respects a normal or slightly subnormal 
wave, a decisive response, from some or other of its parts, 
by this means. 

The actual phenomena in a well-developed case are 
illustrated in the Photog. No 25, which shows the fi^ont 
end of the church of Pertosa, looking at its N.W. end. 
The direction of the nearly horizontal wave that pro- 









i 


p*T 




Sj 


A 


i ■■^■:. 


'* 




ni 


w*- 


■- 


*■-' ^-~- 1f5i 


I^^^^^J 


^R'''<1 




-^ 


■- '^*U 




Kl 


% 


-~w^ ^ ' 


di«w4 


^^ 


'J 


v4 






^P^a 


at 


^ 


"N,*-*^^ 




Mwm 


i 


i 


^'^ A .JL-/) 


-^ 


^li 



RELATION OF VELOCITY AND FRACTURE. 43 

duced these fissures having been almost parallel to the 
west end wall, and fi^om the N. E. to the S.W., or from left 
to right of the picture. The wave of shock was of very- 
steep emergence at Pertosa; but the whole "colline" 
upon which the town is perched, oscillated laterally with 
the wave, and horizontally, or nearly so. The horizontal 
fi^ctures, and those over the door, are due to the emergent 
wave only. 

The force producing fracture and dislocation, impressed 
by the shock, may be viewed as separated into two — one 
just sufficient to fracture the materials, the other to dis- 
lodge them more or less. Both depend upon the velocity 
at maximum of the wave; but the power to produce 
fracture depends much more upon velocity than upon the 
amplitude of the wave, while the energy to produce dis- 
location after fracture depends also upon the latter, which 
determines the time during which the motion of the 
passing wave acts upon the mass. 

The flexibility and elasticity of masonry or brickwork, 
even of the highest quality, in masses of ordinary size is 
small, the limits of distortion without rupture narrow : the 
compressive or extending forces being due to inertia, are 
proportional to M V, and for the same material propor- 
tionate to V only ; and as the amount of extension or com- 
pression, for the unit of length due to any force suddenly 
applied to an elastic solid, is double that produced by the 
same force, if statically or slowly applied, the eflTect of a 
high velocity is to produce fracture with great facility in 
bodies of narrow elastic limits. A wave shock of ex- 
tremely small amplitude, therefore — one so small as not 
to appeal at all alarmingly to our senses — may yet be 



44 FRACTURES USUALLY FOLLOW JOINTS. 

competent to produce considerable fractures in buildings ; 
but in this case the fissures will be found to be close and 
thread-like. 

Were the mass of a wall (viewed as a single parallelo- 
piped) so circumstanced that, its integrant portions, retain- 
ing their relative positions merely, were free to oscillate, and 
then to remain at the points which they occupied at the 
moment the wave left them, having no resilience, in such case 
the chord of the arc of movement at the centre of oscillation 
would be very nearly equal to the amplitude of the wave 
that produced the oscillation ; and this would be equally 
true of the width of a fissure produced in such a wall. Now, 
we occasionally find walls that are extremely massive in pro- 
portion to their altitude, and built of small stones or brick 
laid in bad masonry, and with almost bondless mortar; 
such walls have little or no resilience, and, when thrown 
more or less out of plumb, or fissured, with suitable condi- 
tions, aCFord a rude approximate measure of the horizontal 
amplitude of the earth wave, by the range of movement 
impressed at the level of the centre of oscillation. Some 
examples of this, as observed, will be found in Part II. 

The ocfliesion of mortars and cements to stone or brick, 
in a direction perpendicular to the faces of the joints of • 
the work, is always much less, with the ordinary materials 
employed, than the cohesion of the latter for equal sections ; 
the exceptions being only buildings of very soft tufa, or 
some such stufif. Hence, although fracture and open 
fissures may occur occasionallj^ running right through 
some stones and breaking them across in a building which 
may be acted on transversely, as when very long upon 
their beds, and crossing a line of fissure near the axis of 




ADHESION AND COHESION— CEMENTS. 45 

revolution, thus (Fig. 26) ; it nevertheless almost inva- 
riably happens that the line of fracture, whether in 
stonework or brickwork, follows 
down or along a line of joints, 
producing a jagged or serrated 
fissure, the jaws or serrations de- 
pending upon the length of bed 
of each block or brick, and the 
depth of the courses. ^^'^^' ^^' 

It has been found that the adhesion of Portland cement 
to Portland stone is only 146 lbs. per square inch, while the 
cohesion of the cement itself is 400 lbs. per square inch, or 
the former little more than one-third ; and that the adhesion 
of Parker's cement to granite is as low as 22 lbs. per square 
inch, the cohesion of the cement being 300 lbs. per square 
inch, or less than one-thirteenth. The adhesion of common 
lime mortar varies enormously, with the nature of its 
materials, the sort of stone or brick which it is used to 
cement, the thickness of the joints, the care taken to fill them 
effectually and solidly, the degree of wetness or dryness of 
the mortar itself and of the stone or brick to which it has 
been applied, and the rate at which the mortar has been 
dried during its setting, and the amount of moisture and of 
air to which it has been subsequently exposed. All these 
conditions, or some of them, have been found suflBclent to 
make a difierence of absolute cohesion of more than 2 : 1 
between old Roman mortar consolidated and hardened for 
ages, and good modern mortar allowed sufficient time to be 
viewed as fully set or indurated. When very dry, mortar 
is much more brittle and easily fractured than when wet 
even after complete induration. 



46 



OVERTHROW— PROJECTION. 



Such conditions, and others similar, but tedious to detail, 
must be known to, and constantly looked out for, by 
the seismic observer in the field, or otherwise he will con- 
tinually be liable to compare, as to effects, unlike and in- 
comparable buildings or circumstances. 

The coefficients of cohesion which apply to our equations 
of fracture will be given hereafter. 

Returning now to Figs. 23 and 24. If the path of the 
wave be normal as before, but its velocity and amplitude 
greater than are sufficient only to cause fissures, then one 
or both end walls may be overthrown. If the direction of 
the transit be from a to 6, the end wall a will be pros- 
trated outwards, or in the contrary sense. The end wall 6, 
propped, as before explained, by the side walls, may 

possibly be projected outwards and fall also ; but in most 
instances there will be only fissures produced at its end, 

as in Figs. 21, 22. 

This may be made clearer by referring to Fig. 27. Let 

A E be the path of the wave, its direction of transit being 




Fig. 27. 

from A towards E, and the form of the wave vibration 
cut by a vertical plane, be A jt? C 5' at the end a, and the 
same when it has progi^essed to that b ; bearing in mind, 
however, that the amplitude of the wave, as it actually 
occurs in earthquake, is very great in proportion to its 



DIFFERENCE OF FISSURES AT OPPOSITE ENDS. 47 

altitude, in most cases, indeed in every case of a normal 
or nearly normal wave, and that during its transit the 
whole building is simultaneously in motion. 

The end wall begins to be affected by its own inertia 
at the moment that the forward phase of the wave A to C 
reaches it. The velocity of the vibrating mass increases 
to the maximum at the point j»; when whatever fissure 
may take place occurs, and the centre of gravity of the 
mass begins to move in the direction from C to A, the 
whole turning round the point x at the base. This move- 
ment is continued, though with diminished energy, by the 
wave motion during the second half of its first semi- 
vibration, i. e.j from jo to C, when it passes through zero, 
and now, during the whole of the second semi-vibration 
from C to A, passing through the second maximum at q, 
the motion of the earth is in a contrary sense to that of 
the wall, and of the wave transit. 

It has set the detached mass in motion with a momentum 
= MV, V being the velocity of first semiphase of the 
wave itself at its maximum. It tends to destroy this during 
the second half vibration, by a momentum = M (V — t^), 
V being the difference of velocity in the semiphases. 
During the time of the second half, of the first semi-vibra- 
tion from p (when fracture occurs) to A, the wall continues 
to fall or turn over outwards, and for a little beyond this ; 
but this is now checked by the return or second semi- 
vibration, and unless the angular motion of the mass in 
the time from p to A shall have carried its centre of gravity 
beyond the vertical passing through x, the wall shall not 
fall. If such be the case — i. e.^ if the wall do not fall — a 
X)ntrary motion, more or less tending to restore its position, 



48 FURTHER EXPLANATION. 

is impressed upon it in the return from C through g' to A, 
and it comes to rest, with the fissure somewhat closer than 
it was, at an intermediate moment just after its formation, 
unless fragments have fallen between and prevented this, 
and always assuming that its parts hold coherent. Pro- 
ceeding now to follow the train of action upon the end 
wall 6, the wave affecting almost simultaneously the 
whole building, the two side walls and the end wall h are 
forced forward together, the movement as before, com- 
mencing at the instant the initial movement of the wave D 
reaches them. They both (side and end walls) pass 
through the point r of maximum velocity nearly together, 
and so to E, when the motion of the wave itself is zero, 
and the motion of its second semi-vibration commences, 
which is retrograde as before. 

Fracture cannot occur at the end b during the first semi- 
vibration D r E, because the side and end walls are alike 
urged forward together and at equal velocities: there is 
therefore nothing to produce separation. If fracture, there- 
fore, take place at the end h, it must occur at the point of 
maximum velocity s, in the second semi-vibration, from 
which to D, the motion of the wave continues to pro- 
mote separation; but the momentum impressed at 5 is 
= M (Y — v), whereas at the former end at p it was M V. 
The force necessary to produce fracture of the materials 
being the same at both ends (which is, however, only 
strictly true for absolutely equal velocities), the amount 
of movement impressed upon the mass at the end a, will 
be greater than that at the end i, by the momentum 
due to M 17, (neglecting any small restoration of position 
of a, at the return semiphasc of the wave), and so if 



SQUARE— LONG RECTANGULAR BUILDINGS. 49 

fissures only be produced, those at a will be wider than 
those at b, as was before stated ; or if the impressed move- 
ment be capable of more than this, the end wall a will be 
prostrated ; and that b may stand, but fissured from the 
side walls, or with still greater violence, it, too, may be 
thrown forwards in the same direction as that of the wave 
transit, but to a less horizontal distance. 

Were the building in Figs. 21-23 square in plane, 
instead of rectangular, it will readily be conceived that 
precisely the same phenomena must succeed to a normal 
wave, whose path should be orthogonal to one in the direc- 
tion a ... 6 or in s ... ^ 

If, however, the building be rectangular, and with the 
sides ce and hkof considerable absolute length, and lai^ely 
exceeding that of the ends, and the path of a normal wave 
1>e through them in the direction a...b (Fig. 28), it then 




Pig. 28. 

rarely happens that fissures occur, or occur alone near the 
quoins. 

The wave, as before, passes from a towards b, and the 
side wall c e, as before, moves by inertia in the contrary 

VOL. I. E 



60 OPPOSITE WALLS. 



sense; and were it sufficiently rigid along its length, it 
might tear ofiF from the ends, and fissures occur as before 
at n n, n' n\ the other side wall h k following the movement 
already described for b (Figs. 21-23). 

The whole length of c ^ has an equal velocity impressed ; 
it is unsupported for its whole length, except at the two 
extremities, where it is connected by the quoins with the 
end walls, and held fast by them. It bends into a curve, 
therefore, along its length, bowing outwards most at the 
top and centre of length, and receiving several fi-actures 
m m m, approaching to vertical in direction, owing to the 
length of the curve being greater than that of the ori- 
ginally straight wall. The whole bond of the materials is 
more or less disturbed; but the force of the shock may 
only be such, as to thus curve and fracture, but not over- 
throw the wall. The wall hk m like manner is urged 
forward at the ends h and k by the connection with the 
quoins of the end walls ; but failing also in rigidity, the 
central part is left behind, and bent also by inertia; 
dififering from the first case analyzed in this also, that the 
direction of movement impressed is not in the same direc- 
tion with the wave transit, but reverse to it ; so that here 
both side walls c e and h k move alike in direction, but 
to dificrent extents. The greater velocity V is common 
to both, for both have their velocities impressed by the 
first semi-vibration of the wave ; and were the nature of 
the connection at the quoins the same, whether the walls 
were forced outwards or inwards, both would, coeteris 
paribus^ be bowed alike. From the nature of the quoin 
bond of masonry, however, the end walls at the quoins 
offer much less resistance to the wall c e, being forced 



DIFFERENCES OF EFFECT. 61 

outwards, than they do to the wall h k, being forced in- 
wards, the quoin stones bonded into both walls finding a 
better fulcrum in the transverse resistance of the end walls 
in the latter case. The wall c e in some degree resembles 
a beam merely supported at the two ends, while that 
A ^ is partially in the condition of one encastre at both 
ends, both being subjected to transverse strains ; and ac- 
cordingly the latter usually presents the characteristic 
curve of double curvature when looked at in plan upon 
top, as in Fig. 29. 

The difference in result is practically not great, but 
sufficient generally, to cause the side wall first moved by 




Fig. 29. 

the wave, to have a greater curvature than the opposite 
one, both being more or less fractured. When the shock 
is of sufficient force, however, the wall c e is quite over- 
thrown, falling outwards, and tearing away from the end 
portions, in an irregular, sloping, and hollow curve, following 
along the joints, so that the detached mass is in the form 
in the section in line s s looking towards c e. This seldom 
happens, when the wall h k is devoid of intermediate sup- 
port, without its being more or less prostrated likewise. 
This form of fracture is seen in two of the walls in the 
Photog. (No. 30) of overthrown houses at PoUa, though 
unfortunately somewhat masked by the effects of the 
falling walls having been in this instance precipitated upon 
and against others. 

E 2 



CHAPTER Y. 

FRACTURES COXTINUED — RECTANGULAR BUILDINGS — 

SUBNORMAL SHOCK. 



We proceed next to consider the effects of a Subnormal 
toavej or one whose transit is emergent at an angle to the 
horizon, and in a vertical plane, parallel to two of the walls 
of a rectangular building. 

If the angle of emergence — ^viz. that contained between 
the line of transit of the wave and the horizon be small, not 
exceeding 10° or thereabouts — the effects, when pro- 
ducing fissures or overthrow, can seldom be distinguished 
alone from those of a normal wave. Fissures are produced 
near the quoins, at the tops of the walls, and if overthrow 
takes place the end walls and detached portions of the 
sides, are thrown outwards as already described. In ac- 
cordance with the general law, the fractures tend to place 
themselves at right angles to the direction of wave 
transit. Thus referring to Fig. 31, where the angle of 
emergence (of the wave whose direction of transit is a to J) 
is A I a, the end wall c is thrown back by inertia, and 
that at e projected forward, with a difference of velocity 
= v, as before. As the joints of the masonry or brick- 
work, which the fractures follow, upon the whole run verti- 
cally and horizontally, and as the fracturing force is trans- 



DIRECTION OF FRACTURE. 



53 



mitted diagonally in the direction a d through the side walls, 
fracture occurs in jagged lines in directions perpendicular 
to a (/, the wave-path. The fissures at the end c, therefore, 
commencing at top, very near the internal angles of the 
quoins, run down in the direction pky making an angle 



Fig. 32. 



Fig. 31. 




Fig. 33. 



Fig. 34. 



with the plumb line of the wall c (before disturbance) 
€pk= hia = the angle of emergence. 

The portions of the side walls detached with the ends 
grow wider as they approach the base. They therefore 
make the end wall c too rigid, to turn round upon or near 
its base, as in the former case (Fig. 21), to admit of the 
fissure p k opening ; hence a cross fracture occurs some- 
where below one-third the height of the wall c, as at n, 
which frees the mass and admits of its movement. This 

• 

cross fracture may take any direction downwards from n 
towards ^ dependent upon the nature of the masonry, &c., 
and the mass c chiefly turns over, to the extent of opening 
of the fissure, round the joint at /, or may partly slip upon 



54 EXPLANATION—STEEPER EMERGENCE. 

the fractured joints in ' the direction d a and partly turn. 
When the building is large, and the angle of emergence 
large also, as in Fig 32, this cross fracture is usually a 
curved line, more or less hollow downwards, passing out at 
the quoins at a bed joint as at ^, and in such 'a direction 
that a chord to the hollow curve from n to ^ approaches to 
right angles with p i 

The end e (Fig. 31) is projected forward towards d by 
inertia in the second semi-vibration of the wave. Its 
fissure is more or less exactly parallel with pk for the 
greater portion of its length, but it seldom runs to the base 
of the wall 5, turning out towards d by a horizontal joint, 
somewhat above that level, and at a higher point, as the angle 
of emergence is greater, as may be observed in Fig. 32. 

The reason of this is pretty obvious. The inclined 
direction of the fissure causes it to reach the internal angle 
of the quoin before it comes down to the base of the end 
wall e, which therefore breaks at that level along an 
horizontal line, and all below that, not being detached 
and loaded with the mass above, is unmoved. Cross frac- 
tures may or may not, follow from this fissure towards c, 
dependent on the breadth of side wall, occurring between 
the fissures at the ends c and e^ and upon the angle of 
emergence, class of masonry, and other conditions. 

In Fig. 32 the efifects are shown of the wave when 
emergent at a still greater angle. The train of phenomena 
is quite similar to that just described, but with this addition, 
that where the angle of fracture, tpi = kia= that of 
emergence, is great, and hence the angle ip m great also, 
the overhang of the upper part of the side wall, coupled 
with the momentum in the direction i/?, due to the small 



UNE OF PRESSURE IN THE WALLS. 55 

motion of the wave in altitude^ produce a fracture somewhere 
at 7?i, or more than one, the direction of which downwards is 
much modified by the joints, &c. &c.j of the masonry, and 
is generally nearer to the vertical than exactly at right 
angles top i. 

When the emergent wave produces a sufficient shock 
for complete overthrow of the end walls c and e^ they fall 
as in Fig. 33, leaving the fractures of the side walls 
modified, by the grind of the descending masses. It is 
rarely, however, that a shock of an emergent wave, sufficient 
to throw back one end, and forward the other, occurs without 
the side walls being also thrown, in or out, or both, either 
by transversal wave motion or by secondary actions of the 
felling end walls upon them. 

It was stated above that the direction of diagonal pressure 
through the walls was in that of the wave transit : this is 
perhaps not strictly true, for referring to Fig. 34, if a to 6 
be the path and direction of wave transit, and the velo- 
cities of the wave itself be equal in altitude to s t and in 
amplitude to / m, then the resultant pressure due to its move- 
ment in the forward half of the first semi-vibration is in a b\ 
which, combined with the motion of transit a 6, will give 
a resultant pressure somewhere between 6' and b. As, how- 
ever, the amplitude / m, of the earth wave, appears to be 
always very great with reference \o st^ there is no practical 
error (and much convenience for calculation), in consider- 
ing the line of pressure as coincident with that of wave 
transit. 

If the subnormal wave be orthogonal to that just de- 
scribed, and still afifecting a rectangular building, so that its 
transit passes through the longer sides, these are bowed (if 



5G CHOICE OF BUILDINGS. 

of suflBcient length, «fec.) outwards, at the side first reached 
by the wave, and inwards at the opposite one, diflFering in 
nothing from the efifects of a normal wave upon the same 
building except that these are all less marked, for the same 
velocity and amplitude, the effective velocity producing move- 
ment in the masses detached, being to that of a normal wave 

V 

of equal velocity, as t? : — - ^ e being the subnormal angle, 

or angle of emergence. 

Two other conditions require notice, however, as also 
aflFecting the dislocations produced by subnormal waves. 

If such a wave, with a given value for the angle e, be 
resolved into a vertical and horizontal component, it is the 
latter that is chiefly eflFective in producing dislocation when 
e is small, the former when it is very great : and the effects 
of both are modified more or less by the form of the 
individual blocks of stone of which the wall consists. If 
these are very long in their beds, they offer a most powerful 
resistance to fracture or dislocation by a steeply emergent 
wave; and when thus long bedded, close jointed and 
squared ashlars, prevent any indication of value being had. 

In the choice of buildings, therefore, for arriving at the 
value of e from subnormal fissures, those must be selected 
that are of large size, with walls of brick, or of rubble 
masonry of inferior quality, or at least of small, short- 
bedded stones in proportion to the size of the walls ; and 
fortunately (for seismic researches) there is no want of such 
in the south of Italy. 

Where, also, the value of e is great, two other circum- 
stances come into play to modify the widths of the fissures, 
and even affect their direction, more or less. 



RELATIONS OF FRACTURE AT OPPOSITE ENDS. 57 

Referring again to Fig. 32, the effect of the vertical 
component of the subnormal wave, in its first semiphase, 
tends to drive the fractured mass at the end c down upon 
its foundation, and to throw that at e into the air. 

Gravity, therefore at the former end, acts mt/i the wave, 
in the first semiphase, but against it, at the latter end of 
the building, and tnce versa. But the rhomboidal mass 
of wall between the fissures at the ends c and e is also acted 
on by gravity with the wave, and the result is frequently to 
force down great wedges, such as j9 n m^ which close the fis- 
sure p in such a way as to prevent a certain indication, for 
these wedges being detached all round, remain where they 
descended to last. This is, however, a result of less impor- 
tance, because there never can be a mistake, as to the 
direction along the wave-path of steeply emergent sub- 
normal shocks, in which the seismic vertical is to be found ; 
it must lie to the side at which the wave-path dips below the 
horizon. 

The overthrowing power, and, to a certain extent, the frac- 
turing power of a subnormal wave difiers in the first and 
second semiphase (without reference to the diflFerence due to 
difference of velocity), being proportionate to the perpen- 
diculars to the wave-path, let fall from the centres of oscil- 
lation to the fulcra round which the fractured masses turn. 

This is greatest at the side ^, towards which the wave 
travels, and the tendency of this is to equalize the widths of 
the fissures. Other consequences will be apparent to the 
mechanical reader on considering the conditions. 

From observation of the effects of a subnormal wave, 
therefore, we may be enabled to arrive at conclusions as 
to— 



58 INFERENCES FROM SUBNORMALS. 

1st. The path of the wave — Subnormal. 

2iid. The direction of transit — the fissures being occa- 
sionally most open at the end first reached by 
the wave, and the transit always from tfie end 
tfiat dips below the horizon. 

3rd. The angle of emergence of the wave with the horizon 
being eqirnl to the angle made by the main fis- 
sures (or those transverse to tlie wave-path) toith the 
vertical. 

4th. The velocity of the wave motion may, under 
favourable circumstances, be inferred from that 
impressed upon detached and fallen masses. 

Abundant examples will occur, in the second part of this 
Report, of these subnormal waves, and of their eflFects. 



CHAPTER VI. 

FRACTURES CONTINUED — RECTANGULAR BUILDINGS- 
ABNORMAL SHOCK. 



We have next to refer to the abnormal wave^ or that 
passing horizontally, or nearly so, and diagonally through 
a rectangular building. 

In this case the fissures occur at or near the internal 
angles of the quoins, and are vertical or nearly so, and in so 
far are the same as those produced by a normal wave. In 
a rectangular or square building they are also (the main 
fissures), the same in number (four) generally, but diflFerently 
disposed. If the abnormal angle (that which measures the 
horizontal obliquity of the path of the wave, with two of the 
parallel walls,) is very small, as in Fig. 37, it occasionally 




Fig. 37. Fig. 38. Fig. 36. 

happens that only four main fissures are seen, the alternate 
ones g ' and /' being rather wider than the two others, when 
the direction of the wave is from a to ft, and the sum of 
/ + /» being greater than that oi g' + g, on principles 



60 



PECULIARITY OF FISSURES. 



already explained. And sometimes these are accompanied 
by a much smaller main fissure at n, and either none 
corresponding in the end e^ or one at ?i' still smaller. In 
such a case if the abnormal angle be less than 10'' it 
scarcely admits of decisive observation. 

When the abnormal angle, however, is greater, as iu 
Fig. 38, four main fissures are formed, which, except in the 
case where that angle is = 45°, are alternately wide and 
narrow. Let the direction of the wave transit be a to 6, 
making an angle (in an horizontal plane) less with the wall 
s than with the wall o rl. Then at the end n at which the 
wave first arrives, the fissure n will be narrow, and w will be 
wide, and at the opposite end, ri will be narrow and uf wide, 
and the sum of 2^ + n will be greater than that of vJ + n', 
all being measured horizontally across the jaws of the 
fissures at the same level, suppose at the top of the walls. 

The cause of this is pretty obvious. Referring to Fig. 35, 
if the direction of the wave be a to 6, the force of dislo- 



d 



i- /; <• ^ y/',y/, 

r I-- ■ ' '■'■ ' '-■ 7 













w 



Fig. 35. 



Fig. 39. 



Fig. 40. 



cation of the end wall e A, and the side h w, acts in the 
direction b c, through the centre of gravity of the end wall, 
and oblique to its plane ; it is therefore resolvable into two, 
one perpendicular to the plane of the wall, c /, the other 



ABNORMAL ANGLE FOUND. 61 

parallel to its plane, c A, and both through the centre of 
gravity or of inertia. 

The component c h produces the fissure n. The resist- 
ance of the base of the wall, e A, in the directions d e and 
g hy uniformly along its length, may be resolved into a 
parallel force at / c in the centre of the length and at 
the level of the base, which is below the the level of the 
component force, c /, through the centre of gravity, there is 
therefore a dynamic couple, tending to turn tne wall to the 
left round e A, and this produces the fissure w. 

The fissure n may take place anywhere along the wall 
e hy but usually occurs towards ^, at a distance from A, that 
is to the distance of w from A, approximately as the com- 
ponent / (?, is to that C A, so that a line drawn across from 
n to IT, either at the inside or outside faces of the walls, will 
cross the path of the wave at right angles more or less 
exactly. The position of n, however, is subject to many 
disturbing circumstances, and it never occurs (as the 
proportion of the figures might seem to infer) so far from A 
towards ^, that the masonry of the wall e A, cannot yield 
sufficiently to the shearing strain in the direction of its 
length, to admit of the opening of the fissure. 

Now from the observation of the widths of these re- 
spective fissures, we are in a position to find the angular 
direction in which the path of the wave has traversed the 
building. For referring to Fig. 36, let w be the wider 
and n the narrower fissure, whose widths of ope are propor- 
tionate to the components a and b ; the path of the wave, 
being a to 6, and 0' the angles (together = 90°) made by 
these components with it, and which we require to find, then — 

sin : sin 0' : : a : 6, 



e2 EIOHT SYmfF^-BIC nOURES. 

a and h being eqoal or proportionate to the widths of n 

and Wj therefore — 

a : b :: I : tan 0. 

or 

6 = a, tan 6 

hence 

tan e^ =-; 

from which either the angle ^ or its sine can be had from 
the tables. 

As the path of the wave divides the angle made by the 
two walls (whether the building be square or not) in the 

ratio of 

sin : cos 0, or of sin : sin ff, 

its direction may be easily got geometrically, by an observer 
not accustomed to trigonometry. 

It sometimes happens that eight main fissures may be 
observed, alternately wide and narrow, in a rectangular 
building exposed to an abnormal wave. This only happens 
when the building approaches a square in plan, the ab- 
normal angle being not far from 45"", and the walls very- 
uniform in structure and mass, and built of small material, 
such as brick. 

There are then two fissures, one wider than the other, 
near each quoin, as in Fig. 39 ; four are primary and 
due to the direct action of the wave, the other four seem to 
arise from the shearing strains in the plane of the respective 
walls. ITie case is unusual, but when met with is best 
ngected for scismometry, as likely to lead to error. 

The walls are sometimes, though rarely, found as in 
Mg. 42, the middle portions of c and d first reached by the 
wave, being overthrown inwards, and those a and b leaning 



WALLS OVERTHROWN. 



63 



outwards. This mostly happens from quoins of stability 
disproportionate to the rest of the building, and unfits it 
for seisraometry. 

When the force of shock of an abnormal wave is suffi- 
cient to cause prostration of the walls, they almost always 
fall outwards, and the debris is found as in Fig. 40, a to 6 
being the direction of the wave. 








Fig. 41. . 



Fig. 42. 



When the building is rectangular, and the abnormal 

wave in the direction a to 6, Fig. 41, arrives first at one of 

the long side walls, making an angle of 45° or less, with 

the end walls, the latter are generally fissured vertically 

at n Tiy but the long side walls are also bowed, or possibly 

prostrated ; the greatest amount of curvature being at c and 

t/, and the fissures taking the hollow curved forms, seen 

in the elevation of the wall ^/, the central fissures, being 
secondary or sub-fissures, dependent upon the bowing. 

This form of building is difficult to obtain the abnormal 
angle fi'om, with correctness, and those more nearly square 
should be sought for. 

The remarks that have been made apply to cardinal and 
ordinal buildings alike, the former, when presented, being 
by fiir the best, however, for observation. 



64 INFERENCES FROM ABNORBfALS. 

We are therefore enabled from what precedes, in the 
case of a cardinal building and abnormal icave, to infer — 

1st. The path of the wave. 

2nd. The direction of transit motion. 

Measures of velocity, can scarcely ever be obtained from 
an abnormal wave, as the overthrown masses are quoin 
pieces, which fall attached at right angles, and usually defy 
attempts to ascertain the moments of inertia and dimensions 
of base. 

If the fissures be ckan and well defined^ and the walls 
not too much perforated by openings, or otherwise ren- 
dered irregular, good results can be had ; it is then, not 
important that the walls making angles with each other, 
from which the widths of the directing fissures are taken, 
should be of equal thickness, because the force acting on 
each is proportional to its mass, and the section of fracture 
for equal height is so likewise ; but they must be of similar 
material and masonry. All such conditions, however, will 
be better understood after we have treated of the per- 
turbation of phenomena produced by architectural and 
other features, &c. 



CHAPTER VII. 

DIRECTION OP FRACTURES IN RECTANGULAR BUILDINGS 
BT BUB ABNORMAL SHOCK. 



Wb now proceed to the fourth of our classes of waves, 
namely, the subcJmormal, or the wave whose direction of 
transit, is diagonally in both an horizontal and a xxrtical 
plane, passing through the building ; a waoe which ig at 
once abnormal and emergent. 

On referring to Figs. 43 and 44 the general character of 
the dislocation prodnced by such will be evident. 




Kg. 43. 

The wave emergent ia the direction a to 6 dislodges 
the portions of the quoin c, which it first reaches by 
inertia, during the time of the first semi-vibration, and 
Uiose of the diagonally opposite quoin, are thrown forward 
and often projected out of place also, by inertia in the time 
of the second half vibration. As explained for the abnormal 

VOL. I. F 



68 



WHEN THE OBLIQUITY VERY GREAT. 



corresponding to the subabnormal sought ; and the path of 
the latter will be found in a vertical plane passing through 




Fig. 46. 

a! V. Join o jo, which is in the same vertical plane, and 
also in the plane of the fissures or fractures, mp^ q p^ and 
through the point of the quoin e intersecting a' h\ draw a b 
perpendicular io o p\ a 6 is then the path of the sub- 
abnormal wave, emergent in the direction a to 6. This 
is tantamount to finding the resultant of all the parallel 
forces that resisted fracture, and of course assumes, that 
the masonry fractures equally readily everywhere. 

This is practically sufficiently near the fact, except, 
perhaps, when the horizontal obliquity of the wave- 
path, or abnormal angle is very great ; in that case one 
wall is broken by direct pull nearly, and the other nearly 
transversely, which may give rise to an unbalanced 
couple at u, in a line parallel to ^ m ; and in that case the 
wedge-shaped mass, in place of simply sliding down or 
turning over, in a plane passing vertically through a' b\ 
and falling to pieces, at the base of the quoin, will have a 
small amount of rotation, either to the right or left of that 
plane ; and the centre of gravity of the mass of debris, 
will be found correspondingly posited, to the right or left 
of the base of the quoin. No case has been observed 



SUBABNORMAL EMERGENCE FOUND. e9 

by the author (amongst very many of the class), in which 
from this cause a perturbation was produced, that could 
render the determination of the wave-path uncertain in 
the horizontal element, by more than 2° or 3°. 

The arc corresponding to the sine ofteo^orofse Oj viz. 
6 and d' of a former case, gives the abnormal angle or bear- 
ing, of the horizontal element of the wave-path, if the 
building be cardinal : or this, + or — the azimuth of the 
walls, gives it if ordinal, ?ind the angle o e u = 6" is equal 
the angle of emergence with the horizon, to which it is 
alternate. 

The whole of the preceding may be readily done 
trigonometrically, and by an observer accustomed to such 
operations that method will be found more advantageous, 
as greatly economizing time on the ground, and enabling 
the results to be worked out at leisure. 

Let the dark lines m e^ q e he the level top of the ad- 
jacent walls (Fig/ 48 bis), e /the quoin, e the solid angle 
at top, n, tr, /), the points of fracture in those lines. 




As e / is plumb, me/, and q e fj are each 90°. Let 
gem, any angle be given, and also the distances, ne,ioe,pe, 
the two former proportionate to/and/', the component forces 



ro 



TRIGONOMETRICAL 



that produced the fractures at n and w^ /" the vertical 
component corresponding to these; u the intersection of 
the polar (or direction of emergence of the wave), with the 
plane passing through n, w and j9. 
The angles made hy op and a b = 90°. 

Calling the angle q em = (f) 

n e =: 6 
w e = & 

ueoczd"=epo= angle o 

emergence 



51 



yi 



?5 



?? 



jy 



55 



51 



55 



55 



55 



55 



55 



w n e = <r 
nwe=T 
cr +T =2 p = 180° — </) 



The arc of - 0' = >/. 



The line 



n ^ 


^ 


L 




■f 


2/7 e 


= 


M 


= 


f 


p e 


= 


N 






n 


z=. 


X : 


= 


W i 


e 


— 


y 






r e 


— 


Z 


— 


R 

2 



R being the common resultant of /, f, f\ in a b. 



Then L + M : L - M ; 

tan ^(e- e') = 



<t> — ^ 



: tan | <f> : tan i (0 
tan^ <^ (L - M) 
L + M, 



-e') 



9 



But sin <) : L : : sin (0 : 2 Y 
as tlie the diagonals s e and w n mutually bisect 



SOLUTION. 71 

- ^ L sin p 

' ^ sin 

it as L + M : L — M : : tan I /t> : tan ^ (cr — t) 

^ ^ ^ L + M ' 

d -7 T = ^ p, + arc corresponding to, tan ^ (a- — t) 
-7 AT = I p — the same arc. 

gain, sin T : L : : sin <^ : 2 x 

X = — : — — = the distance from one fracture to the 

sm T 

ler diagonally opposite 

2 y = the resultant of/ and /' 
N :y : : 1 : tan 0" 

tan = :^ 

lich gives the angle of emergence, or that made by the 
lar a, 6, of the subabnormal wave, with the horizon. 

Cos 0" : y : : 1 : ^ 

y 



z = 



cos 0" 



y 

X ^,, = R the common resultant in the polar a 6, 

cos 0" ' V y 

d, 2 y tan 0" = /' the vertical component. 

An extremely easy method may be practised of finding 

5 path of a subabnormal wave by an observer in the 

Id. 

Referring to Fig. 44. Let a line be stretched across 

5 top of the walls (or anywhere below that, but hori- 

atally), fi\)m the exterior or interior angle of fracture. 



72 GEOMETRICAL METHOD. 

on one wall, to that on the other, w to n, and the let^th 
be divided la the proportion of«wtoen;if from the 
dividing point 'p, a plumb-line be dropped, it will lie in 
the vertical plane in which the path of the wave is situate. 
Let now another line be stretched, or a light straight 
edge of wood be held, between the points 'p and p (corre- 
sponding to the line o p, of Fig. 46) ; lastly, stretch a line 
from the point 'p, so that it shall be square to the line 'pp 
and holding it in the hand, " sight it," to coincide visually 
with the plumb-line : this line or string will then be, in 
the path of the subabnormal wave, and its azimuth 
and inclination, may each be at once got, by compass and 
clinometer, or by two measurements, without the latter 
instrument This method admits of quite suflBcient accu- 
racy, if the fractured-out pyramid be not too lai^e, but 
such, that either a straight edge (a straight rafter or joist 
will answer, of which plenty may generally be found loose 
about) or a stout cord can be stretched tight across, from 
w to n. The direction can be thus obtained within a 
degree or two at most. 

It is obvious that if the path of this wave, be referred 
to its component path, in either of the 
two walls, by a plane, normal to a verti- 
cal plane, and both passing through the 
wave-path, then the former plane, will 
cut the surfeces of the walls, in direc- 
tions perpendicular to the fracture in 
each respectively, as in a' b' and a" b" 
^' ' (Fig. 44), which coincides with what was 

stated before, as to the general fact, that the lines of 
fissures from subnormal waves (i. e. those emergent in the 





MODIFICATIONS— ILLUSTRATIONS. 73 

plane of the wall) are perpendicular to the path of 
emergence. 

The position of the point /?, or the distance down the 
quoin, at which the two adjacent fractures meet, apart 
from any variations caused by diflferences of masonry, &c., 
depends both upon the velocity, and the angle of emer- 
gence of this wave. For referring to Fig. 47, if a^ b\ be 
the path of emergence, referred to ^^ 

one of the walls, and w^ jf, be the 
line of fracture therein correspond- 
ingy then as the mass thrown out 
is greater, as the velocity is so, 
and as the angle of fracture with Fig. 47. 

the quoin is constant, while the emergence is so, it follows 
that if the velocity be reduced, the fracture will be some- 
where as at a; y, still parallel to to* p\ but higher up, and 
vice versdj and so for any other emergence : but if the 
velocity being the same, the angle of emergence vary, 
then, in order that the line of fracture may still continue 
perpendicular thereto, the point p must ascend or descend 
along the quoin as with the path a 6, producing the line of 
fracture tv /?, which, when it makes a very acute angle with 
the quoin, and therefore the angle of emergence small, and 
the velocity also great, may even follow back along the 
walls as to j; ^, so that the point p^ would fall below the 
base of the wall, if the lines of the fractures were 
produced. 

In the Photog. No. 49, which gives a very good illus- 
tration of this class of fracture, as observed at Auletta, 
this was actually the case. In this view, one of the other 
large fissures, corresponding to n and k (Fig. 45) may 



74 PERTURBATIONS BY SUPPORTS, ETC. 

be remarked, as also in Photog. No. 50, at Paterno 
church. 

In the Photog. No. 51 (Coll. Roy. Soc.), also in a street in 
the town of PoUa, a mass, thrown by an extremely oblique 
subabnormal wave, will be observed to the left hand, in 
which the eflfect of this obliquity, and of the miserable class 
of *' nobbly " rubble masonry, and of a floor within, have 
perturbed the phenomena, as respects the wall, seen most 
nearly in the plane of the picture. The direction of shock, 
was in this instance, nearly along the line of the street, 
towards the spectator, and a little firom the left, towards 
the right ; and in farther evidence of the general direction 
here, it should be remarked that the whole side of the 
street to the right hand where the fronts of the houses are 
nearly in the line of shock, and supported as well as held in 
by the floors, &c., against the small transverse component 
of shock, all remains standing, though propped here and 
there ; while at the far end of the street, the fronts of the 
houses in the street running obliquely across that going 
from the spectator are all down. 



CHAPTER VIIT. 

SHOCKS OF VERTICAL OR NEARLY VERTICAL EMERGENCE- 
EFFECTS ON RECTANGULAR BUILDINGS. 



We now arrive at the fifth and last class of waves, viz., 
those of 'vertical or very nearly vertical emergence^ upon 
which it is necessary to make some remarks. 

As a strictly normal or abnormal wave, i. e. with per- 
fectly horizontal transit (unless by reflection) is impos- 
sible from a focus beneath the surface, so an absolutelv 
vertical emergence is in strictness limited, to the single 
point of the earth's surface vertically above the focus, or to 
the seismic vertical itself. Inasmuch however, as in reality 
the disturbance producing impulse is not confined to a mathe- 
matical point, but (whatever be its nature) extends over a 
greater or less, and in all cases a very considerable area, 
and lies also at such a considerable depth, that lines ex- 
tending fi:'om it to the surface make but small angles with 
each other ; so a tolerably large area is found in the midst 
of every earthquake-shaken region within which the angle 
of emergence is so steep that it may be viewed, as respects 
the effects of the wave, as practically vertical. 

In the preceding remarks upon the four first orders of 
wave-paths, we have viewed the wave itself as of one 
sheet and the movement of any particles in the wave to 



76 



MOVEMENTS OF 



be forward and backward in a right line or in an eUiptic 
or some other closed curve, in a vertical plane, neglecting 
the transversal movement (which is small) for the present 
This, although perhaps not physically true, was sufficient 
for our purpose. 

Were we at liberty to consider the vibration of the wave 
with vertical emergence performed in like manner, the 
movement of any point of matter upon the surface due to it 
would be limited to two motions — one directly up and down, 
due to the amplitude, and the other forward and backward 
horizontally, due to its altitude and to the senses. The 
movement would thus be similar to that of a normal or 
subnormal wave. The universal testimony, however, of 
those who have experienced these vertically-arriving shocks 
is of a twisting and wriggling motion in diflFerent planes^ 
violent in its changes of direction, and attended by a move- 
ment up and down of much greater range^ to which the 
word • " sussultatore " is often applied. It seems highly 



Fig. 52 A. 



Fig. 52 B. 




Fig. 53 c. 



Fig. 53 D. 




probable that the path of a wave particle moving normally 
or nearly so, may be elliptic, as in Fig. 52 a, in a vertical 



THE VIBRATING PARTICLE. 



77 



tC^Ot ^g'^^- 



¥ig,55JL 



Pig. 560. 



plane, and with a smaUer transversal vibration performed 
in a horizontal plane as in Fig. 52 b. ^ The actual relation 
of altitude and amplitude^ so far as observation yet is 
afforded, seem more as in Fig. 53 c, or even in a far 
higher ratio to each other, and the transversal vibration 
still smaller, as in Fig. 53 d, so that in normal or slightly 
emergent waves the transversal movement is little noticed, 
(as, indeed, is true pro tanto of the movement in altitude) ; 
hence, as stated, we may neglect 
for present purposes, the transverse 
movement altogether as respects such 
waves. 

In the case of vertical emergence, 
however, the path of a moving par- 
ticle being in one vertical plane 
elliptic, and the major axis being the 
line of transit, will have the form 
of Fig. 54 E, in a vertical plane at 
right angles to the former, and in 
an horizontal plane at the earth's 
surface the path will be as in Fig. 
55 H. In ascending through hetero- 
geneous formations even the more 
complex forms of Fig. 56 g and f, 
or Fig. 57 K and l, may be those of 
the path of the wave particle, the ver- 
tical being the movement of largest 
range, in every instance. In either 
of those cases the sensible effect 
upon the earth's surface must be the same as if bodies, 
besides being lifted up and down, were alternately whirled 




Vig. Mb. 



M 



(0@}^Kg-«* 




Fig. 57 L. 



Fig. 57 z. 



78 TWISTING STRAINS— NOT " V0RT1008I." 

round in small circles in the directions of the bent arrows 
1 and 2 in Fig. 58 ¥• Iii vibrating elastic masses having 
special and pendulous vibrations of their own, when set in 
motion by the wave, the axis c d may rapidly, though with 
a much slower relative movement, rotate in the direction 
of the external arrows or in the reverse one. The formi- 
dable torsional and wrenching strains which are known 
to arise from vertical shocks, are most probably thus pro- 
duced. 

It must be remarked, however, that these torsional 
strains — " Yorticosi " of the Italians and Mexicans — ^must 
not be supposed capable of producing those twistings 
of objects upon their bases, such as vases, chimneys, 
obelisks, &c., of which we shall record many examples, but 
which are due to other circumstances first explained by 
myself several years since.* 

A continuous jarring movement, consisting of a rapidly 
arriving series of waves, moving in a horizontal plane, as 
in Fig. 57 L, often occurs, and in lofty buildings, such as 
churches or towers, when the time of torsion vibration of 
the building itself (once set in motion), happens to be iso- 
chronous with that of the wave vibration, twisting strains 
of enormous violence result. 

The eflfect upon the walls, then, of the vertical wave is 
chiefly to produce fractures which are transverse to the 
lilies of twisting distortion. As the twist is alternately in 
opposite directions, these fractures cross each other, the 
opposite contained angles being double, those of the lines of 
maximum torsion strain with the vertical. These motions 
being accompanied by rapid up-and-down ones of much 

• * Trans. Roy. liish A«ui. / vol. xxi. p. 1, 1846. 



GRAVITY ACTING WITH VERTICAL SHOCK. 79 

greater range, each distinct story of the building acquires 
a separate momentum of its own, in virtue of the weight 
and attachment to the walls, of the floors and objects 
upon them. All the fractures tend therefore to separate 
and close again, as the wave makes its transit ; and the 
several masses, moving horizontally at the same time, 
with a rotation alternate and increasing as it ascends the 
building, the replacements do not often coincide with the 
displacements, and in a few seconds the stability of the 
walls may be so far destroyed, that the whole falls 
to the ground in ruin the most complete. Fissures 
running horizontally or nearly so from the quoins are 
not unfrequently observable where the emergence is very 
steep or nearly vertical, examples of which may be ob- 
served at both sides of the N.W. wall of the church of 
Pertosa (Photog. No. 25, page 42). 

With vertical or nearly vertical emergence also, gravity 
acting with inertia, in the first semiphase of the wave, 
upon the masses of masonry situated directly above door- 
ways, windows, and other such apertures, their tendency 
to come down is great ; and hence, not only are vertical 
fissures formed over such openings, but they are open loidest 
at bottom^ one of which will be remarked breaking across 
the stone lintel over the west door of Pertosa church 
(Photog. No. 25), but diagonal fissures crossing the piers 
between windows, where there are doors or other opes 
beneath, in a lower story, of which examples occur in the 
Palazzo Palmieri at Polla and will be observed in the 
Photogs. 178 and 180, Part 11. 

It is upon the heavy Italian roofs and floors, however, 
already described, that the most instant and formidable 



80 ILL SUITED FOR MEASUREMENTS. 

effects are produced by vertical emergence. Upon these 
the vertical velocity produces a moment of inertia acting 
directly downwards, and therefore favoured by gravity. 
Arched roofs, groining, and that form of arched ceiling 
constructed of hollow pottery, then spread the walls, as 
they come down, and falling upon the floors below, bring 
them down in succession. The details of movement will, 
however, be best given further on. 

Upon the whole, the phenomena of vertical emergence, 
afford little ground for exact observation, with a view to 
trace the elements of the shock, and their limited occur- 
rence is not to be regretted, on this ground. When once 
seen they present general features by which they can 
almost always be recognized with tolerable certainty, but 
not such as will enable us to ascertain directly, the line 
which produced downwards, should intersect the centre of 
impulse beneath the central field. That must be sought 
for otherwise, by observations at a greater distance from 
the seismic vertical, where the wave movements have 
become more uniform, and less complicated. When 
ascertained by the method of intersections of wave-paths, 
aided, if occasion serve, by determinations of velocity of 
transit, applied to the values of the angle e, its correctness 
may be tested and controlled, within certain limits, by the 
coincidence or not, of the focus thus obtained, with the 
observed area of vertical phenomenay somewhere within which 
the seismic vertical is situated. 



CHAPTER IX. 

CONDITIONS AS TO FORM AND STRUCTURE IN BUILDINGS, 
WHICH MODIFY THE EFFECTS OF SHOCK — FIVE PRIN- 
CIPAL CONDITIONS. 



It will now be necessary to refer to the special eflfects 
produced, by the architectural figure, and other particular 
conditions of buildings, &c., upon the principal phenomena 
due to the shock upon them, as just described. The 
treating of this might give rise to almost endless details ; 
reference will therefore only be made to a few of the 
salient conditions, and their modifying eflfects, from which 
the intelligence of the observer can deduce, all others that 
may come before him. 

What has preceded has been exemplified, by an ima- 
ginary roofless rectangular building, on level ground, and 
without any apertures. We have now to discuss how the 
actual conditions of buildings as we find them (having 
those of Italy in view primarily, however) affect and 
modify the results- We may discuss this under the fol- 
lowing heads of eflFects, produced by the wave of each 
class, as modified by the following conditions, viz. : — 

1st. The form, magnitude, height, and unsymmetrical 
character of construction. 

VOL. I. 



82 DISLOCATION, COMBINES FRACTURE AND OVERTHROW— 

2nd. The form of the surfece or foundation, and the 
relations of buildings in juxtaposition, as in 
towns. 

3rd. The class of masonry and materials, their flexi- 
bility and elasticity, &c. 

4th. The reactions on roofe and floors, and of these 
again, upon the other parts of buildings. 

5 th. The eflFects of apertures in walls, as gateways, 
doors, windows, &c. 

After these some observations upon the perturbing 
etfects produced by the physical and geological fea- 
tures of the country, will conclude the first part of this 
Report. 

The final dissolution and fall of every compound struc- 
ture in masonry, occurs by the successive development, of 
two stages of dislocation. Were it possible that a building 
could be overturned by the shock, as a whole, the con- 
ditions of its overthrow, would of course depend simply 
upon its *' moment of stability." This, however, owing to 
the imperfect bond at the joints, and the relations of mag- 
nitude, to the strength of the materials, can never occur, 
except in the case of very lofty towers or minarets, spires, 
or single columns, &c. In such a case the mass may be 
overturned, and dissolution then takes place principally by 
the stroke of its fall to the ground. 

In all other cases, however, the great fractures are pro- 
duced in the first instance, which break up the whole, into 
a number of distinct, and more or less independent masses. 
The immediately subsequent movements of each of these, 
depends upon its own moment of stability, in as far as 
it is unsupported, or unaffected by the stability, or by 



DISINTEGRATION— DIREC5TI0N OF FRACTURE— FALL. 83 

the fall of others. The disintegration of the building — 
viz., whether it shall split up at all — depends, as we have 
seen, upon — 

1st The direction (as to horizontal obliquity and 
emergence) and the velocity of the wave, 
directly, and the density of the materials. 

2nd. Upon the tenacity and bond of the materials, 
inversely, and upon the form and magnitude 
of the structure. 

Both these relations being modified, by the elasticity and 
flexibility, of the materials. 

The directions of the great fractures producing disintegra- 
tion depend upon — 

1st. The direction (as to obliquity and emergence) 
of the wave ; i. e., on the abnormal and emer- 
gent angles. 

2nd. The form of the structure as a whole, and of its 
several parts, or details, previous to severance. 

Lastly. The fall of each separate mass, if then severed, 
depends upon its own moment of stability. If any such 
separated mass fall, it does so in the direction of its least 
horizontal dimension: or as for any practical purpose of 
seismic observation, the moment of inertia due to the 
oversetting force must lie in this direction (for otherwise 
the mass falls by twisting), we may limit the consideration 
to that case. 

If t be the thickness of the bed joint of masonry upon 
which the mass overturns, cut by a vertical plane passing 
through the centre of gravity of the mass and the line of 

o 2 



84 FRACTURE— PALL— MECHANICAL CONDITIONS. 

transit of the wave ; i, the slope of the joint, if any, to the 
horizon ; r, the fraction of ty that measures the distance of 
the point where the line of resistance cuts it, from the 
mid-length ; r', the distance from the bisecting point of t, 
to where it is intersected by the vertical through the centre 
of gravity of the mass, W its weight, and 2 its moment 
of stability; then 

2 = W X (r ± r') ^ cos i, 

according as the line of resistance and the vertical through 
the centre of gravity, are at the same or at opposite sides 
of the bisection of t. 

The weight of the mass (whatever be its form, assumed 
approaching regular), may be expressed 

^ being a factor, determined by the angles that its three 
dimensions ?, 6, and t make with each other, and on its 
form, and 5 the specific gravity of the masonry. Therefore 

2 = ^ (r + /) cos i % Ibt^ y, S. 

If F be the force necessary to fracture the mortar at the 
joint /, acting in the direction of the wave transit, 

F + ^ (r ± r') cos i % Ibt^ % h 

is equal the total resistance of the mass to being overturned 
by the force of the shock, acting at the centre of gravity 
in the same line, but opposite direction 

V X <^ X /6^ X 5- 
For similar forms of the fractured and separated masses. 



BUILDINGS OP VARIOUS FORMS. 85 

therefore, and like direction of emergence and velocity of 
wave, the resistance to fracture F, depends upon the co- 
hesion per unit of surface and total area of fracture, and the 
resistance to fall S, upon the density of the masonry, the 
height, the breadth, and the square of that one of the two 
horizontal dimensions, which lies in the direction of the 
shock, and may be called the thickness. 

The mass being severed free^ from all others, by fracture, 
it depends upon the value of (r ± /), and upon the emergent 
angle of the wave, whether it shall fall forward, in the 
direction of the wave transit, or in the reverse one. And 
from the nature of the applied force (being that of inertia), 
S disappears. 

Such are the general conditions as to equilibrium, upon 
which the fracture and fall of the separated masses, pro- 
ducing final dissolution of the building or structure, 
depends, and from which, equations for various architec- 
tural forms and conditions may be deduced. 

The circumstances of fidl of simple rectangular buildings 
have now been explained. Cruciform buildings, such as 
churches, are aflfected much in the same ways, the twelve 
sides of such a building being, in fact, capable of being 
viewed or arranged, as separable into those as three simple 
rectangular ones. 

Polygonal buildings are rare, and when the number 
of sides are few, and the length of each considerable, do 
not present features materially diflFerent. 

Cylindrical buildings, or conic frustra, however, which 
may be viewed as polygons of an infinite number of sides, 
have some peculiarities. 

Whatever be the direction of shock, if horizontal, upon 



86 CYLINDBIC TOWERS. 

SQch a buildiog, its effects are the same. The distinctioQ 
of normal and abnormal wave does not exist as respects 
them ; and miless the angle of emei^nce of the wave be 
extreme, or nearly vertical, the lines of fracture are the 
same in every case, viz., vertically through tiie axis and 
transverse to the line of shock. This arises from the &ct 
that the area of fracture, and therefore the total resistance, 
F, doe to it, augment rapidly as the angle of its obliquity 
with the vertical, through the cylindrical walls increases. 
So that although the direct tendency of the wave a J is to 
throw off a cylindric ungnla, ed c (Fig. 59), by a fracture 
perpendicular to its direction in e /, yet 
the surface of fracture is so great, and 
its direction at either side of the vertical 
plane of the wave transit, so obliquely 
through the joints, that the building 
always parts in the weaker line, by dia- 
metrical vertical fissures through k m. 
The separated masses have now each a moment of stabiKty, 
the fraction i', in which is enormous, being equal to the 
radius of the cylinder or the base of the cone ; and hence 
the fragments of such towers are seldom overturned. 

Where the value of F is small, as in the very bad 
rubble masonry of the ancient towers, and the angle of 
emergence considerable, however, we have instances of the 
mass thrown out assuming the form of a curved ungula, 
obviously by the fracture comracncing vertically, and fol- 
lowing down the joints gi-cuUttim from k \a p, and thence 
to c 5 of this a remarkable example occurs at Atena. 

When the emergence is still more vertical, and the 
shock powerful, a number of nearly equidistant fissures 





APSES— COLUMNS— CAMPANILES. 87 

form round the top of the walls, commencing vertically, 
and masses are thrown out, each carrying down with it 
an ungular-shaped toe, so that the tower becomes shorn 
around the summit at a greater or less distance down, by 
the descent of several separate masses from it, in the form 
of Fig. 60, and, as better seen in the Photog. No. 61, page 
42, at Marsiconuovo. The original fissures are here, no 
doubt, produced chiefly by the twisting movements, trans- 
ferred quite round the walls, by transversal vibrations as 
referred to when treating of the wave of 
vertical emergence. 

This applies but to a limited extent 
to the semi-cylindrical "apses" which 
form the chancel ends, of so many of the 
more ancient churches. These generally Fig. eo. 

split oflF at or near the re-entering t:i'.^\es of the quoins, by 
which they are joined on to the body of the building, 
if the wave transit approach a line, transverse to that 
diameter; if otherwise, the walls of the "apse" split ver- 
tically in the direction of the opposite diameter. 

Towers of extreme altitude and very narrow base, such 
as slender minars, single columns, lofty campaniles, &e., 
involve a number of complicated and curious considerar 
tions, as respects their resistance to fracture and to over- 
throw by shocks. 

In these the elastic modulus, density, and range of flexi- 
bility before fincture of the masonry, the time of vibration 
of the structure viewed as a compound elastic pendulum — 
together with the direction of wave transit, and the relation 
that may subsist between the amplitude of the wave, its 
maximum velocity, and the pendulum time and range of 



88 BUTTRESSES, ETC. 

vibration of the tower— all are elements. It is not requi- 
site for our present purposes, however, here to pursue the 
investigation. 

The eflfect generally, of want of symmetry in the severed 
masses, is to reduce them by further dislocation, prior to 
complete overthrow. For example : a portion of a uniform 
wall, severed by transverse fissures from the remainder, 
but having a buttress of its own or of less height some- 
where along its length, is again transversely broken close 
to the buttress, the moment of resistance to fall being 
diflFerent in each. The relation of the buttress to the wall, 
as a support against transverse forces of a statical sort, is 
no longer the same, when the overthrow is produced by 
a force applied with the rapidity of the wave of shock ; 
there may not be time, to transmit its own stability to the 
remainder of the wall.^ 

Where the buttress is at the same time a tower rising 
much beyond the height of the remainder of the building, 
these generally tend to mutual destruction; the primary 
fissures occur at the junctions or near them; the walls 
and the tower have diflFerent times of vibration, as eliastic 
pendulums of diflFerent lengths, and whether by chance iso- 
chronous or not, produce mutual damage, by their impulses 
upon each other. This is peculiarly striking, in the case 
of many of the meaner class, of Italian rural churches, 
where the belfry tower is built into one of the quoins of 
the main rectangular building, the two adjacent side walls 
are frequently completely destroyed by transverse rocking 
of the tower ; although the latter may have only suflFered 
Assuring at the lower portions, and that which was above 
the level of the church walls be overthrown. 



^9 


i 


,'~"~* ■■!'- ■j-^TT^-'- V 






HIGH TOWERS. 98 

High towers and of narrow base, fall as one mass, 
breaking oflf diagonally somewhere above the base, what- 
ever be the direction of the wave. When, however, the 
angle of emergence is very steep, a certain amount of 
shearing force is introduced, and the angle of severance 
becomes very sharp likewise, so that a sharp angular 
"aiguille" of shattered masonry remains standing, often 
bearing a considerable proportion to the whole original 
height A remarkable example of this form of fracture is 
given in Fig. 62 of the tower of the monastery of Santa 
Dominica, at Montemurro, sketched from the top of the 
Palazzo Fino, although in this instance probably due only 
to accidental causes, and not to steep emergence. Isolated 
fragments thrown from the summits of such towers, owing 
to their own velocity of pendulous vibration, do not always, 
by reference to the obseiTcd distance of projection, repre- 
sent without correction, measures of the true direction or 
velocity of the wave. They are thrown like a stone from 
a sling, with a certain velocity and direction due to the 
shock, plus or minus, another, or perhaps a diflFercnt direc- 
tion and velocity, due to the proper motion of the tower; 
of this the observer requires to be on guard. 

Unsymmetrical consti^uction of buildiivj, always involves 
unsymmetrical plienomena of dissoluUioii. If compelled to 
adopt such a building, (in lack of better,) for observa- 
tion, the first thing to be done to disentangle the 
phenomena, is to consider the effects, due to the want of 
symmetry alone. If, for example, we find the opposite 
walls of a cardinal church, one standing and the other 
prostrate, the wave transit having been abnormal, and 
nearly in their lines of length, the first point to be ascer- 



90 UNSYMMETRIC BUILDINGS. 

tained is, was the prostrate wall symmetrical in form and 
structure with that remaining. Unless the effects of the 
roof may have overthrown it, we shall generally find, that 
the fallen wall was either of much inferior masonry, or 
smaller thickness, out of plumb originally, or full of 
windows and doors, the standing wall being solid. 



CHAPTER X. 

EFFECTS DUE TO FLEXIBILITY AND ELASTICITY OF THE 
MATERIALS IN BUILDINGS — FLEXIBILITY OF BRICKWORK. 



All the preceding observations of course have taken no 
account as yet of the reactions produced on the walls by 
roofs and floors: they refer to the walls considered as 
standing alone. The actual extent of elastic flexibility 
of stone and brick masonry, especially of the former,- is 
not commonly considerable ; and unfortunately, as yet, no 
precise measures of these exist for any class of masonry. 
Were it not for this property, however, no building would 
stand, even a very moderate shock ; and were the velocity 
of the wave confined within the limits of the velocity of 
the centre of oscillation of the structure, considered as an 
elastic compound pendulum, whose time of vibration is due 
to the length of a simple pendulum equal to the height of 
that centre above the base, and were the amplitude of the 
shock within the limit of elastic displacement of the 
masonry, &c., at that centre, no building would be thrown 
down. 

A well-constructed brick and mortar wall, of 30 or 40 
years' induration, and 40 feet in height, unsupported, of 
two bricks, or 1*60 feet in thickness, has been observed by 
myself, to vibrate nearly 2 feet transversely at the top, 



92 EXAMPLES-SPECIAL EFFECTS. 

before it fell, in a storm of wind ; and that not nntil after 
many snch oscillations had disintegrated many of the 
horizontal joints, and produced several vertical fractures. 
The point of greatest flexion traversed along the length 
of the wall, as each oblique gust of wind impinged upon it, 
like the waves of a rope suspended from one end, and 
jerked transversely at the other. 

An octagonal brick chimney stalk, with a heavy granite 
capping 160 feet in height above the ground, and 15 feet 
diameter at the base, was observed by me, instrumentally, 
to vibrate in a moderate gale of wind, when a few months 
built, nearly 5 inches at the top. 

These are illustrations of the extent of flexibility in 
good brickwork, which possesses it in a far higher degree 
than stone masonry, the bond of the mortar being better, 
the flexibility greater, both in the brick and thick mortar 
joints, these very numerous, and the elasticity more nearly 
alike in both, than in stone masonry. When the joints 
are much fewer in proportion, the stone relatively to the 
mortar, highly clastic and rigid, and the bond, so far as 
adhesion of the mortar is concerned, small, (indeed, in the 
case of many hard, siliceous stones, such as granite, almost 
nil,) the result of this difi^erence is, that a well-built and 
indurated brick wall, when fractured, breaks indifferently 
nearly, through joints and bricks ; but in stone walls, the 
line of fracture is confined to the mortar joints, with rare 
exceptions, the rigidity of the several blocks, transferring 
the whole of the compressions and extensions due to the 
strains to the mortar alone. From this cause, it was 
observed very uniformly throughout this earthquake region, 
that when brick construction was superimposed upon stone 



IJMESTONE MASONRY— WORST AND BEST. 93 

work, as not unusual in churches, the brick-work, although 
of so much less density, fell as one mass, with fractures 
of severance along the lines of junction of the two ; and 
viee versdj when the brick-work, as in a few cases, was 
beneath, and stone-work above, and when the latter was 
thrown, if it did not push the brick-work over in its fall, 
the latter remained comparatively unharmed. 

The limit of flexibility of stone masonry exposed to 
earthquake shocks depends, to an immense extent, upon the 
flatness and superficial area of the beds of the individual 
stones, and the completeness with which " breaking joint " 
and " thorough bonding " are preserved in the setting. 

When the masonry consisted of rounded, lumpy, quad- 
rated ovoids, of soft limestone, as already mentioned in the 
general description of the poorer and older towns, and of 
which the Photog. No. 63, of a part of PoUa is an 
example, the whole dislocation occurred through the enor- 
mously thick, ill-filled mortar joints; and almost all 
buildings thus formed, fell together at the first movement, 
in indistinguishable ruin. In the Photog. No. 64 (Coll. 
Roy. See.) of Pertosa, a poor, but more modern town, 
the class of masonry was a little better, and, as may be 
remarked, the ruin less complete. 

Where, as in a few examples observed, the masonry was 
of the best class (and such as would be so recognized in 
England), the buildings thus constructed, stood absolutely 
uninjured in the midst of chaotic ruin. Some examples of 
this will be found in the second part — none more striking 
than that of the Campanile of Atena, a square tower of 
about 90 feet in height, and 22 feet square at the base, in 
which there was not even a fissure, while all around nearly 



94 AGGREGATE TENACITY— SERRATED JOINTS. 

was prostrate. This tower was, however, also aided by 
iron chain bars, built in at each story. The great viaduct 
carrying the military road at Campostrina is another 
example. Indeed, it was evident, that had the towns 
generally been substantially and well built, or, rather, the 
materials scientifically put together, very few buildings 
would have been actually shaken down, even in those loca- 
lities where the shocks were most violent, and their direc- 
tions the most destructive. Thus the frightful loss of life 
and limb, were as much to be attributed to the ignorance 
and imperfection displayed, in the domestic architecture of 
the people, as to the unhappy natural condition of their 
country, as respects earthquake. 

In a wall of parallelopipedal blocks, properly over- 
lapping and breaking joint, the aggregate tenacity, of a ver- 
tical serrated transverse line of joints, may be represented, 
as Professor Rankine has shown, by an equation of the 
form 

W 4- 1 

T = n-^--f,S %bht 

the last letters being tlie dimensions of the wall at the 
serrated section : n, the number of courses ; /, the co- 
efiicient of friction, which may equally be taken as the 
co-efficient of o^/herence of the mortar, irrespective of its 
own coherence, and rf, the specific gravity of the stone or 
brick. Unfortunately, we still need better experimental 
data as to the adhesion of mortar, in directions both 
parallel, and transverse, to the bed surfaces, to enable us to 
apply the numerical results to earthquake-applied strains 
producing vertical or inclined serrated fissures. The like 



• SUDDENLY APPLIED FORCE. 95 

difficulties do not arise with horizontal transverse frac- 
tures. 

The strain is here applied almost with the rapidity of a 
blow. Ahnost the whole stress falls instantly upon the less 
elastic mortar joints, at their surfaces of contact with the 
stones, when exposed to direct pull, and the mortar joint 
parts off from the stone with a resistance of only om-half 
that due to its statical adherence, or to its statical cofierence. 
This fact is rendered familiar to the senses, by the facility 
with which two bricks from an indurated building, that would 
require a slowly applied load of perhaps half a ton to tear 
them directly asunder, may be caused to part and drop 
asunder, by a slight blow from a hammer upon one of the 
bricks while the other is held in the hand. As applied to our 
subject, this sufficiently indicates, that the portion of the 
total force of shock required to produce fissure, or horizontal 
fracture of the base, of the severed masses, to permit over- 
throw, is, when these are large, relatively very small ; so 
much so, where the masses, are large in relation to the sur- 
faces of fracture, and the co-efficient/, of adherence very low 
as in the case of the Neapolitan provincial mortar, that 
it may be frequently neglected in calculations of seismic 
statistity. At p. 139, et seq., will be found the method of 
calculating the velocity due to fracture of the horizontal 
mortar joints, at the base of walls overthrown, which is the 
most important and frequent case of fracture that occurs, 
in seismometric observation. 



CHAPTER XI. 

SECOND CLASS OF CONDITIONS MODIFYING EFFECTS OP 
SHOCK — FIRST ASPECT OF RUINED TOWNS. 



This disposes, by anticipation, of the third class of modi- 
fying conditions. As respects the second, nothing is more 
remarkable and puzzling to an unpractised observer, who 
enters a town situated upon tolerably level ground, than 
the apparent caprice by which the fall of the buildings is 
characterized. He finds one whole side of a street cleared 
down; turning into the next, within a few hundred feet, 
he needs be on the watch, to discover any signs of injury. 
Further on, whole districts of streets have disappeared, and 
one heap of rubbish, stones, and beams occupies their 
place ; yet, not far off, long lines of houses are but fissured. 
In some large streets the houses are down here and there, 
in the most irregular order, some of the very loftiest stand 
pretty safely — some of the humblest are in dust. 

These abrupt changes from safety to destruction are still 
more remarkable, if the town, in place of resting upon the 
plain, or on pretty level ground, occupy the summit and 
flanks of some " colline," or conoidal hill. Here, perhaps, 
at one side of a line passing over the crest of the hill, nearly 
everything is demolished ; at the other, little damage has 
been done. Until by the help of such observations as have 



ANALYSIS OF PHENOMENA. 97 

been described, apon some one or more of the injured but 
not overthrown large and cardinal buildings, the observer 
has got some clue to the direction of transit of shock, he 
is completely bewildered ; and if he has no clear notioa 
formed on this point, he will be much disposed to coincide 
at first, with the opinions chattered around him by the 
principal townsmen, the Syndic, the Judice, the Sotto 
Intendente, &c., who accompany him, and assure him that 
the shock was in evm/ direction " tutti, tutti direzioni," 
— that it was " orizontale e vorticoso ;" and point out, in 
proof of tiiis, that the buildings have actually fallen in 
all possible directions, which is undeniable. 

A town formed of streets of adjoining and abutting 
honses, may be viewed, as respects each block of buildings, 
as a vast cancellated single structure, in which, in certain di- 
rections at least, every portion adds stability to all the rest. 

The lai^r the single block of houses, or the longer the 
line at the aides of a street, if the shock be in the direction 




Fig. 65. 



of its length, the less, e<Btms paribun, is the injury done ; 
but there are other causes also in play. Those of some 

VOL. I. H 



08 ANALYSIS 

of the principal pheDomona may be best illnstrated by 
reference to Fig. 65, an imaginary block plan, of part of 
an earthquake-shaken town. Whole districts at ^ ^ are 
prostrated. At both ends of the great church, and about 
m, and along the street from h to e^ houses have fallen, and 
others are grievously injured; yet these are perhaps 
amongst the best built and least ancient houses in the 
place. Passing along the main central street, after de- 
bouching over heaps of stone at e, it is found, that along 
the greater part of its length, fissures here and there, a few 
chimneys, or a side wall down, as we look up some " vico," 
are all the signs of earthquake visible. 

The great church, when examined, tells us that the hori- 
zontal direction of shock was from a to 6. Returning now 
over the ground, and examining the^lace with the compass 
in hand, we find that the main street presented its length to 
the direction of movement ; its stiff front and rere walls, 
its multiplied floors, have saved it. The street <? to A, on the 
contrary, although of houses of the same date, height, and 
character, &c., is nearly destroyed ; it was nearly transverse 
to the line of movement. The street at 7n has escaped 
much better, though much injured, yet it is nearly parallel 
with e A, and the houses are as high if not higher ; but we 
find they arc some of the newest and hest-built houses in 
the town. Some houses at the right of the Chiesa Madre 
are thrown down, but no others in the Piazza, have suf- 
fered. The rubbish has probably all been cleared from the 
Piazza in the market-place, and we cannot tell which way 
the houses fell, but we look at the fallen apse or campanile 
or transept, and find that it fell against one of these, and 
upon these houses. We now get out of the highways of 




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CONTINUED— EXAMPLES. 99 

the place, and find a large district whose length is almost 
parallel with the well-preserved main street and yet is a 
mass of rubbish. No house stands to tell us of what they 
were ; but, on examining the character of the stones, and 
of "the timbers, the shattered doors and window-shutters, 
and so forth, we find this was one of the poorest quarters 
of the town, and, as always happens (except in rapidly 
growing cities), one of the oldest. The buildings here are 
in heaps, because before the shock they were tottering and 
ready to fall. The whole matter has become clear, and the 
feet has been learned, that entire towns give little informa- 
tion to the seismic observer, and that but of a general and 
often uncertain character — that single buildings are his 
proper objects. 

Had the direction of shock been a! to b\ in place of w^hat 
was assumed, a little examination of the figure will make 
it evident that the whole train of phenomena would have 
been changed. Hence the prodigious complexity of phe- 
nomena presented by towns that have been subjected to two 
or more shocks in diflFerent or in orthogonal directions in 
qmck succession. It is needful to state these circumstances, 
trivially simple as they appear, because hitherto they have 
been nnnoticed and unregarded by previous earthquake 
dewribers. Even the scientific reporters of Calabrian and 
other earthquakes, who multiply such facts, seem to have 
had no clear conception of their cause and connection. 

The Photogs. Nos. 66, (67 and 68, Coll. Roy. Soc.,) 
Olnstrate also some examples. In No. 66, a street in Polla, 
the direction of shock, was nearly perpendicular to the plane 
of the picture, and from the observer. The face of the 
houses, built well and with a batter, here receiving the 

H 2 



100 VARIOUS SPECIAL CASES. 

shock nearly end on, remained in great part standing, and 
SO saved all beyond them, while all lower down that part 
of the city was destroyed. 

In part of a street in the humbler part of Pertosa, 
Photog. No. 67, (ColL Roy. Soc.,) the shock was nearly 
in the perpendicular, to the plane of the picture, and from 
the observer. One side of the street, that on the right 
hand, is almost quite down ; the opposite one was compa- 
ratively safe. The houses were much of the same character 
at both sides ; but on one side the shock piitled out the 
fronts, that have fallen away from the roofe and joists, 
which had no hold upon them owing to the method of 
construction, while it pressed inwards^ against the firmly 
resisting edges of the floors and roofs the other side, 
which the wave, in its return vibration, had not sufficient 
velocity in its horizontal component to bring down. , 

In Photog. No. 68, (Coll. Roy. Soc.,) some of the highest 
houses in PoUa were left standing tolerably safe, though 
full of apertures, and arched galleries in front ; while the 
same street, lower down and near the front of the picture, 
was choked with the ruins of houses, of only half the height 
or less. The former were new and well built in comparison 
with the latter. 

If in place of the town standing upon pretty level 
ground, as previously assumed, it stand upon a hill summit, 
and on its flanks, the diflcrence of devastation, at diflferent 
sides, is usually great. If, as in Fig. 69, the shock emerge 
in the direction a—b, the buildings at the right and left, are 
difierently affected, because their grasp upon the ground at 
their foundations is dificrent, the relative direction of 
emergence diflcrcnt (as will be more fully examined when 



EFFECTS OP POBM OF THE GKOUND. " -" 101 

treating of the relations of geological formation to shoiik), 
and often (as at Saponara) chiefly because the houses that 
fall at the steep side to the left hand, fall gainst and upon, 




Fig. 69. 

Uiose below them, and tJiie accumulated ruin falls in an 
avalanche of rubbish down the hill-side. 

So also if, in place of a steep angle of emergence, the line 
of shock were nearly horizontal, as irom left to right, in the 
figure, the whole of the steep side of the town, during 
the first half vibration, tends to &11 from the hill-side, and 
tberefore aaxiy from all the natural abutments that their 
foundations excavated from the hill-side afford to the sides 
nearest the hill-top, but all of which generally are opera- 
tive m favour of the houses at the other side of the hill. 

This difference may be much compensated by the nature 
of the rock formation beneath the town, as well as by the 
form of the hill, &c., but this belongs to a future part of the 
subject 



•••• 

• • • 



• • • 



• "• 



• •• 






• • •• 

• • • 









••• • 



» 



'• 









* 



CHAPTER XII. 

EFFECTS OF SHOCK UPON BUILDINGS — THE 4tH MODIFYING 
CONDITION —RELATIONS OF FLOORS AND ROOFS. 



Let us proceed now to the relations of floors and roofs to 
the shock, and the eflFects of both in modifying its action, 
immediate and final, upon the other parts of the buildings. 
The common construction of provincial Neapolitan floors 
and roofs, has been already briefly described. Were the 
floors of an earthquake-shaken house perfectly homogeneous, 
formed, as if of a single parallel plate of cement or 
beton, self-supported and free from all timbering, the lines 
of fracture would be almost perfectly regular, and follow in 
accordance with those of the side and end walls ; so that 
with a normal or subnormal wave, fractures would extend 
crossways, parallel to the walls, and generally uniting the 
fissures wherever these were situated in the latter ; and with 
an abnormal or subabnormal wave, the fractures would be 
diagonal, at right angles to the line of transit of the wave, 
when viewed in plan upon the floor, and generally uniting the 
wall fissures situated in the adjacent walls, or diagonally 
opposite ; while with a vertical or very steeply emergent 
wave, fractures would be found crossing each other in an 
horizontal plane at right angles, or nearly so, but having 
any degree of obliquity to the planes of the walls, depen- 



EFFECTS OP EACH OF THE THREE CLASSES OF WAVES. 103 



dent upon the direction of the line of wave transit, if very 
steeply emergent, and upon the form and relations, as to 
horizontal figure and height, of the buHding — or to the 
latter conditions only, if the transit were perfectly vertical. 
The three cases are illustrated in Figs. 70, 71, and 72. 
In either of the two latter, large portions would become 

Fig, 70, Fig. 71. Fig. 72. 







Ji- 


0_ 


\f- 


B-f 


L 






F 


E 


^ 


i; 






E 


^ 


+4 


: 






rn 


Fi 


3=fi 





Fig 73 Fig. 74. Fig. 73. 

detached, and would fall, leaving other portions, as in 
Pig. 73, still adherent and supported by the walls ; while 
in the first case, if the width transverse to a — b (Fig. 70) 
were suflScient, the segments detached by the parallel 
fractures, would break again transversely, by their own 
weight at or near the mid-length, and also close to the 
walls, and then fall. 

So fer, account has been taken only of direct seismic 
forces in the plane of the ^floors, hat in the subnormal, sub- 
abnormal, and vertical waves, the inertia of the floor 
itself is broi^ht into play transversely to its own plane, and 
all the displacements by fall just mentioned as due to 
gravity alone acting after fracture are produced upon an 



104 FORCES IN THE PLANE OF 

exaggerated scale by the introduction of this force con- 
spiring with inertia at the moment of shock vertically 
downwards. 

Now these are, in fact, precisely the forms of fracture 
and destruction, observable in these heavy floors of concrete 
and tiles, so far as they are left free, in a limited degi^ee, by 
the constraint of the planking and joists beneath. 

The joists and planking, are as one mass, and move 
together, and parallel to their respective lengths, under 
forces parallel to either, whether horizontal or slightly 
emergent. The union, however, is not suflBciently com- 
plete, and the jointing of the planking is too rough and 
open, to prevent "racking" by diagonal forces, as in 
Figs. 74, 75 ; and as the several quoins give out un- 
equally, in the case of diagonal wave transit, the buildings 
are no longer truly rectangular in plan, and so in this the 
floors follow the walls. If the wave be normal or sub- 
normal, and the joists lie parallel to its line of transit, 
the wall at the end first reached by the wave draws off* 
from the ends of the joists embedded in it. The floor itself 
more or less as a whole, follows the wall, and the other 
ends of the joists draw from the opposite wall, all during the 
first semi-vibration of the wave. During the second semi- 
vibration, the whole floor returns by inertia, in the opposite 
direction to its first movement, and following in the direc- 
tion of transit of the wave, thrusts back again the previously 
drawn ends of the joists, into their sockets in the wall h 
(Fig. 76), and the mass is stopped by coming into contact 
with the interior face of this wall, against which, it strikes 
with enormous violence, the edge of the planking and of the 
concrete striking the whole length of the wall, almost at the 



THE FLOORS AND TRANSVERSE TO SAME. 



105 



same instant and at the same level. This only happens when 
the direction of shock is pretty nearly in the line of the 
joists^ 2&ayh (Fig. 76). In such a case, the floor is almost 




Fig. 77. 

certain, if of any considerable magnitude, to bring down the 
end wall, upon which it strikes with the power of a 
** battering ram." 

The sockets of the joists, (inserted, as, has been stated, 
they commonly are, into the bare masonry without tossal or 
bond timber,) become partially occupied by fragments fallen 
into them, and on the return into them of the drawn-out ends, 
these thump out holes, right through the wall, or shake the 
bond of the masonry effectually. The wall 6, for the height 
of the story below, falls outwards, or in the direction of move- 
ment of the floor and wave, but for that portion above the 
shaken floor, it falls inwards, or upon the floor itself, and, at 
the moment after the whole support, of the floor beneath at 
that end has been withdrawn. The end b of the floor there- 
fore sinks and falls, and the other end of the joists, so far 
as they still remain in their sockets, act as levers, thus 
loaded, and prize the wall at the end a asunder, so that 



106 FLOORS OVER EACH OTHER— PLANKING. 

it falls, likewise, very commonly outwardly, but, by possi- 
bility, in the direction towards the floor also. This chain 
of events, one of the most potent in the destruction of 
domestic buildings in Italy by earthquakes, is illustrated 
in Figs. 76, 77. 

When there are two or three floors, over each other, that 
thus carry away the walls, they all (walls and floors) go 
towards 6, the walls wholly falling outwardly. It will 
readily be conceived, what an inextricable mass of confused 
ruin, houses thus thrown down present, for the side walls 
that run parallel with the joists (or beams), fissured before 
transversely to the line of wave transit, are always more 
or less shaken down also, by the tremendous descent of the 
floors and walls, upon them falling. 

If the line of transit of the wave, be in an orthogonal direc- 
tion however, parallel to the planking^ and therefore trans- 
verse to the direction of the joists, these having hold of the 
walls through the intervention of their sockets, the opening 
of the fissures in the walls on which the joists rest (due to 
their own inertia), is augmented by the inertia of the floor. 
The joists, or some of them, in advance of the fissures towards 
the end b in the side walls, going forward with the flooring 
and side walls, drag the planking from the remainder of the 
joists, tearing out or bending partially the spikes, or break- 
ing short the trenails ; and the main weight of the flooring, 
thus freed from constraint of the side walls, runs forward 
as before, and though to a less extent, induces the same 
train of events, that have already been described. 

And when the line of transit of the wave is thus trans- 
verse to the direction of the joists, the same set of phe- 
nomena result from both the first and the second semi- 



RESILIENCE CONSPIRING WITH WAVE. 107 

vibrations of the wave, and with effects proportionate to 
the velocities in each semiphase. The concrete and tiles of 
these floors adhere but very slightly to the planking on 
which they are laid, and the bond is so destroyed by the 
first slight movement, that the thick and heavy laminum 
often slides whole, or in large fragments, upon the planking, 
and batters the walls, already inclining outwards, indepen- 
dent of any constraint from the timbering. 

When the wave is vertical, or of very steep emergence, 
the heavy tiled roofing, generally comes down upon the 
upper floor, almost at the instant that the inertia of each 
floor, acting at its centre of gravity in the opposite direction 
to the wave transit, tends to bring it down also. The 
impulse of the suddenly-imposed load of fallen roofing, con- 
spiring with the effect of the shock, from which the resilience 
of the joists (if able to have done so at all), have not had 
time to recover, bring down the upper floor; the united 
load falls upon those beneath, and the whole are carried 
away in succession to the ground. 

But, circumstances of building and of shock may be such, 
that the floor does not give way, but that, as an elastic 
plate or beam, supported and encastre at opposite ends (for 
the planking and concrete, we must bear in mind, have no 
insertion in the walls, and but slight connection with them), 
it merely bends downwards by its own inertia and that of 
whatever be upon it, under the upward stroke of the wave, 
as by a load suddenly applied over its whole surface. In 
this case, on the commencement of the second semi-vibra- 
tion of the wave (or downward stroke), the bended timbers 
commence to straighten themselves again ; their resilience, 
as a constant force acting through the versed sine of cur^ 



108 NATURE OF THE "SBALZA." 

vature, carries them upwards beyond the line of their passive 
position, at the same moment^ that the second semi-vibration 
relieves the load upon them, by its inertia acting against 
gravity. The consequence is, the middle parts of a 
tolerably large floor, spring up with amazing velocity and 
power, beneath those who may be upon it, furniture is 
thrown upwards and towards the walls, tiles are projected 
upwards from the floor surface, masses of the concrete 
sometimes dislodged, and persons standing or moving on 
the floor are thrown upwards, and lose their balance. 

Such is commonly the source of the strong impres- 
sion of those who have experienced steeply emergent 
shocks, of an upward movement, unbalanced by any corre- 
sponding dowBward one, to which the title " sussultatoreo " 
is usually given, and which, when very violent, is called 
" sbalza " by the Mexicans. Of the latter, some remark- 
able examples will be recorded, as narrated to me. 

Floors are not always, sources of increased injury how- 
ever ; they may occasionally act the part of props, to walls 
that if unsupported for their entire height, would have been 
prostrated, by normal or other waves of the first four classes. 

This can only occur, when the line of transit is transverse 
to the direction of the joists, and when the end wall is in 
advance of the wave, 6, and, consequently, the edges of 
the floors also, are intersected by a wall whose plane, is 
parallel with the line of transit, as in Fig. 78 ; or when 
some other such fulcrum, resists the forward motion of 
the floors themselves, and enables them to hold together 
the side walls by the insertion of the joist's ends, and so to 
save the wall at c c, d d, by cancellating the structure, in 
vertical and horizontal directions. The planking connect- 



FLOOR FISSURES. VALUABLE INDICES. 




ing the joists, it will be seen, here plays the part of a 
connecting stay to the side walls cd, c d, at the return 
stroke or semi-vibration of 
the wave, tying them toge- 
ther by the inserted ends of 
the joists, whose distances , 
they themselves fis. 

When the floors have ' 
given way as described, the 
building is usually too for ^'«™- ^^•'^■ 

destroyed, to be of any use for seismometry ; beyond this, 
that a clear comprehension of the mode of &11, will always 
enable the general dire(^on of shock to be roughly inferred ; 
but where the floors, beii^ heavy and good, have not 
wholly &llen, nor the walls, bat that these are fissured, 
and have given oat unequally, and the floors also are 
fissured, but not completely displaced, very valuable indi- 
cations may be obtained from them, as, for example, in 
Fig. 79, where the walls /c eg, are fissured and given oat. 
We obtain excellent measures of the extent, of this in the 
directions f e, g e, by measarements at the edges of the 
concrete or tiles, and inside the walls, controlling those of 
the fissures, which sometimes- (though rarely) are not 
measurable at all, and from the directions of the fissures of the 
floor we may obtain evidence, of another wave movement 
when occurring in the direction c — d, transverse to the prin- 
cipal one — b. In &ct, the observation of the floors, is 
only second in importance to that of the walls. The one 
illostration given, however, most suffice to indicate a large 
and veiy varied class of questions to which they may be 
made to give response. 



CHAPTER XIII. 

EFPBCTS OP SHOCK UPON BUILDINGS — THE 4tH MODIFYING 
CONDITION CONTINUED — RELATIONS OP ROOPING — 
MODES OF FALL. 



As respects roofing of the ordinary class, of heavy timber 
framing, with or without common rafters superposed, or 
with heavy lathing only, to carry the ponderous ridge and 
furrow tiling already described; all that has been stated 
of the modes of giving way of flooring applies also, in 
like cases of wave transit, to it ; with this addition, that 
it frequently happens, owing to the low pitch of Italian 
roofs, and the enormous weight of the tiling, added to the 
rudeness of workmanship in the framing, and the want of 
sufficient iron work in fastenings (iron being a dear com 
modity, and none made in the kingdom but by the old 
Catalan process, and all imported heavily loaded with duty) ; 
from all this, the roof frames often give way at the tye 
beams, and the principal rafters then thrust out the side 
walls, as the roof falls by the shock, if either emergent 
steeply or vertical. This is almost always the case when 
the roof is of considerable span, as over churches. In such 
roofs, " common rafters," are laid upon longitudinal 
" purlins," or beams stretching across the principals ; and 
when the direction of wave transit is anything nearly hori- 
zontal, and in or near the line of the ridge of the roof, the 



HOW AFFECT THE WALLS. Ill 

whole roof rocks endways upon its bearings at the level of 
llie eaves or " wall plates," and these purlins act as "batter- 
ing rams '* upon the gable walls, which they almost inva- 
riably carry away wholly or in part. A good illustration of 
this is afforded by Photog. No. 80, of the west end of the 
church at Picerno, where the common rafters are nearly 
all gone as well as the tiling, from the right hand side of 
the roof, and the front gable nearly all thrown down by 
the E. and W. rocking of the roof, and the inertia of the 
gables themselves. When the wave is nearly normal, and 
transverse to the ridge of one of those large heavy tim- 
bered roofs, with the ends of the principals resting directly 
upon the masonry, of the top of the side walls, or occa- 
sionally perhaps upon a heavy wall plate of ill-squared 
timber, the inertia of the whole is so enormous, that in 
almost every instance, the wall first reached by the wave 
was thrown outwards, by the shove from the roof and its 
own inertia together, and the whole roof then dropped 
nearly plumb down upon, the area of the building, crushing 
everything before it. 

From this tiled roofing, however, whether carried away 
completely, or only disturbed upon the walls, very few 
seismometric observations of value, can be made. The chief 
of these consist, in the occasional indications afforded, by the 
amount of draw-out of timbers from their sockets in the 
walls, either longitudinal or transverse. The tiling itself, 
is so loose, the interstices between the overlaps so great, 
that it is very seldom partiaUy disturbed, never probably 
in sitUy unless by nearly vertical emergence of wave, it 
is either carried away altogether, or presents no signs of 
movements that can be distinguished, from the ordinary 



112 GROmBD AND DOMED ROOFS. 

irregularities, looseness, and twistings, of the lines of 
tiles. 

There are two other forms of roofing, viz. arched or 
groined, and dome roofe, which frequently occur in the 
better order of churches, and which become highly in- 
structive. Upon these some observations will be necessary. 
The Neapolitan churches, which are nearly all either Lom- 
bardic, Roman, or Palladian, in style of architecture, are 
very commonly roofed with solid brick (or more rarely 
stone) arching. The monasteries and public civil build- 
ings, are also very frequently arched, both in floors and 
roofe, and many of the better built and more modem 
villas and palazzi, are so likewise, more especially in 
the upper stories and corridors. Semi-cylindric arching, 
and hemispherical domes, are the more common forms 
of church covering of this character, built in brick and 
mortar, with timbering and tiling over that, or with solid 
stone sloping pavement, for the outer skin of the roof. 
Groining of intersecting cylindric arches, is not unusual, 
in the monasteries and civil buildings, and hemispherical 
doming, intersecting and connected by cylindric arch-bands, 
is often met with in the more recent churches. The 
arching in villa architecture is of comparatively late date, 
and executed in hollow pottery laid in mortar. 

The inertia of all these forms of roofing is very great 
Intersecting arched groining universally splits along 
the crowns of the arches, whenever the direction of wave 
transit is transverse or oblique, to the line of the axis or 
springing, and with moderate amount of emergence. If the 
wave be very abnormal, and the structure pretty large, 
transverse fissures at right angles or more or less oblique 



VAULTED ROOFS— ANGLE FOR GREATEST OVERTHROW. 113 

to the former also form. When the emergence is steep, 
three orders of fissures, if not more, are produced in large 
arched vaults, one along the crown, and two others parallel 
to it, and distant from 40° to 50° at either side of it. 
Where the lateral movement amounts to even a very few 
inches, the detached masses descend, between those standing 
at each abutment, enough to destroy equilibrium, and either 
they fall through, and more or less, from both abutments 
follows, or the whole comes down together. When the 
emergence is steep, the two lateral fissures, are further 
removed from that at the crown, and a very moderate 
vertical shock, suffices to send outwards, both side walls or 
abutments, and the whole vault drops between. 

The gable ends or semi-tambours of such cylindric 
vaults, consisting (essentially) of a semicircular plate of 
masonry resting upon its diameter, level with the vault 
springing, give out at top at both ends of such vaulted 
roofing, when the direction of wave transit is along the line 
of the axis or near it, forming a large fissure transversely, 
at the junction of the gable and vault ring (or near it), 
which is usually, most open at the end first reached by the 
wave, from reasons obvious from what has preceded ; the 
difference is greater as the wave is more subnormal, as 
gravity conspires with inertia then, to bring out the first 
reached gable, but acts against inertia, in the second. 

When the wave is subnormal and transverse to the axis 
of a cylindric vault, its greatest overthrowing power is 
exercised, when the angle of emergence is such, that the line 
of transit passing through the centre of gravity of the vault, 
(or of its transverse section), also passes through the joint 
(either at one side or the other of the crown), that is re- 

VOL. I. I 



114 CYLINDRIC VAULTING. 

moved 45° from it, which, as the centre of gravity is about 
0*64 r, the mean radius of the arch ring being r, gives 
an angle of emergence of about 15°. Hemispheric 
domes, are also most readily, fissured or overthrown, by 
a wave of small emergence. Where the emergence is steep, 
the fissures run in curved lines, transverse to the line of 
transit, and cross each other more or less, when viewed in 
the line of the vertical axis, and few or none of them pass 
through the crown. When apertures are formed (such as 
Ughts) in the dome, and especially if near its springing the 
fissures are directed from their upper angles, and great 
sector-shaped masses are dislocated. An almost vertical 
or completely vertical shock does not seem to affect domes 
at all as much, as horizontal or subnormal ones. 

The directions of the fissures in any case, depend not 
merely upon the direction of the wave transit, but also 
upon the planes of the curving joints, of the structure and 
upon its details of construction, to such an extent, that 
general principles can only to a very limited extent be 
made available for deductive observation from domes. 

The Photogs.Nos. 81 (82 Coll. Roy. Soc), illustrate the 
general character of the fall of curvilinear roofing. No. 81 
is of Tito Cathedral, where the emergence was steep, and 
the roofing a combination of cylindric vaulting and domes ; 
it shows (see p. 99) the form of a very formidable double 
fissure in the crown of cylindric arching or vaulting, and 
the intermediate fragments given down by inertia ; beyond 
this fragments of the lateral domes are visible, and more 
fully seen in No. 82 (Coll. Roy. Soc). In No. 168 (see 
p. 296), the fall of the cylindric vaulting of the nave and 
chancel at Polla is seen, and its effects in fracturing and 



EARTHQUAKES OF ANCIENT ROME. 1 15 

sending outwards the side walls at its fall. No. 84 (Coll. 
Eoy. Soc.) is an exterior view of the apse of the church of 
St. Maria Maggiore at Yignola, where the wave was sub- 
abnormal, with moderate obliquity and emergence, and 
where the fragments of the tower and of parts of its conical 
roof, were projected on to the roof of the church. 

Conical or prismatic roofe of this sort over towers, being 
generally of timber were not frequently disturbed ; when 
fractured, however, they are so in ways extremely capricious 
and perplexing. The partial fall of the tiled roof of the apse 
at Vignola, was due to the drawing away of the heads of the 
principal rafters from their support by the movement of the 
curved walls consequent on the large fissures visible in them. 

It may be remarked that generally no feature of archi- 
tectural construction is more characterized by its destruc- 
tive effects upon the remainder of the edifice when shaken 
than are those vaulted and domed roofs. Their inertia is 
enormous, the centre of gravity is high above the walls, 
and they are deficient in tenacity and flexibility. They 
therefore not only are dislocated and fractured separately, 
but their rocking to and fro as a whole on the tops of the 
walls leads to the destruction of the latter. Upon examining 
the gigantic ruins at Home, of the Imperial Baths of Titus, 
Caracalla and Nero, &c., an eye that has become con- 
versant with seismic observation, at once perceives that 
the destruction of these enormous edifices, was but little due 
to the feeble hand of the barbarian, and was mainly pro- 
duced by the earthquakes that desolated the city between 
the fifth and ninth centuries, acting thus upon their massive 
vaults and domes of brick-work. 



I 2 



CHAPTER XIV. 

EFFECT OP SHOCK ON BUILDINGS — FIFTH MODIFYING 
CONDITION — EFFECTS OF APERTURES, ETC. IN WALLS. 



We at length come to the fifth and last head of con- 
structive modification, as affecting and affected by, the 
shock, viz., the effects of wall apertures, windows, doors, 
&c. A few words of illustration will be sufficient for this. 
Assuming the simplest case, as in Fig. 86, of a normal 




Fig. 86. 

wave; whenever the wall is pierced by one or several 
rectangular or other apertures, it may be viewed as divided 
into different segments such as that ef^ gh^nk^ each having 
a separate moment of stress of its own, and giving rise 
to a separate dynamic couple, the extremity of one arm 
being in the centre of gravity, c, the other at the base and 
junction with the similar adjoining segments, the ten- 



FRACTURES OVER WINDOWS. 



117 



(lency of the oscillation being, to alter the angular position 
of each separate mass, and to produce separation from the 
others in directions parallel to ^ n, to ^ /, and to g h. 

The fissures tend to form, as in a solid wall, perpendi- 
cular to the line of transit of the wave ; but as in a solid 
wall (all of horizontal courses) these must also follow the 
joints, so must they here where the joints above all such 
rectangular apertures are those of arch voussoirs at various 
inclinations. Hence, when the wave is normal the fissures 
form through the nearest vertical arch joint generally, 
and through to the next aperture above or below, as in 
Fig. 87 ; but when subnormal the fractures are through 



cHEiMMiMffi 



■mmmm 



t; 



S 2 



t 




^ 



a> 




Fig. 87. 



Fig. 88. 



the joints of the voussoir nearest square to the line of 
transit, as in Fig. 88 ; and very generally in such a case 
the fissures run, from the angles of the apertures. Hence 
the angle made by the joint, of the plate-band arch or low 
segment arch, above a window or doorway, through which 
the fractures run, with the vertical, forms an approxi- 
mate measure of the angle of emergence. The precise 
position of the fracture is of course varied by innumerable 
minuter conditions, such as variation of thickness in the 
wall, difiFerence of strength at difierent points otherwise 



118 DIAGONAL FISSURES. 

similar, and many others, which nrnst be looked ont for, 
when the phenomena are found perplexed. 

Abnormal and snbabnormal waves, produce like effects 
here, to normal and subnormal, except that they are by 
the former produced in two planes of walls, meeting at an 
angle usually right, and accompanied by disturbances 
transverse to the plane of each wall. When the wave is 
of very steep emergence or vertical, then diagonal fissures 
are produced in two directions crossing each other, and 
often accompanied by vertical fissures also, from causes 
obvious on reference to the statements already made as to 
the fissures in solid walls due to such waves. 

A remarkable example of fissures of this sort will be 
found in a subsequent page, occnr^ 
ring at Folia. Their general charac- 
' ter is that of Fig. 89. 

These figures apply to wall aper- 
tures of the usual moderate size of 
windows and doors. When very 
much larger and wider, and covered 
at top with plate-band arches or 
stone lintels, two or more fissures 
Fig. 89. often take place, by the opposite 

movements of the first and second scmivibration of the 
wave, and large fragments fall out. 

The usual character of fracture in arches of considerable 
curvature may be illustrated by the Photog. No. 90 (Coll. 
Roy. Soc.) ; but many others will occur in the succeeding 
pages. When the width of arch aperture is very consi- 
derable—eighteen, to twenty or thirty feet for example — 
and a large mass of wall overhead, fractures transverse 




STEEP EMERGENCE— LARGE ARCHES. 119 

to the plane of the wall, usually occur not only at or near 
the crown of the arch, but (as in the case of roof 
vaults) 40° to 50° or even more, at either side of it, and 
the mass above probably descends more or less, and 
then secondary diagonal fissures are prodnced by its 
descent, which have no relation to the angle of emergence 
of the wave, and must not be confounded, as indicatory 
of it, with fissures previously produced. An example of 
this will be recorded in the city of Naples. 

Very steep emergence with large semicircular arches, 
usually produces two sets of fractures also, as in Fig. 91. 
The wave emergent a to b, produces , 
the fissures o/ and o n, and those at ' 
c and g, probably in its first semi- 
vibration ; in the second semi-vibrar 
tion the mass c e f tends to rotate 
round c in a direction a to 6 and / 
to e, but the instant it is displaced 
the weight of the hanging mass kfn 
breaks the whole across at ^ by a 
nearly vertical fissure ; hf drops ver- "^'s ^i- 

tically a little, and when e e k has resumed its state of 
repose, the right-hand side of the soffit of the arch is per- 
manently a little below the left. This might readily be 
mistaken (alone) for a displacement due to a normal wave. 
■ Some examples will be given in the narrative also of 
other singular secondary effects upon the atones and vons- 
soirs of arches by continued oscillation produced by normal 
or subnormal waves. 

When the angle of emergence becomes extremely steep 
it may occasionally be observed that little or no trace of 
obliquity of fissure is to be found. The wave, in fact, 




1'20 



EMERGENCE NEARLY VERTICAL. 



emerges so nearly vertical that its horizontal elements are 
those mainly eflfective in dislocation, and produce only 
fissures by resolution, where there are piers and window 
apertures horizontal ones, as in Fig. 92. 



; 




Fig. 92. 

Stone staircases, the steps of which are bedded into the 
walls, often produce most complicated eflfects, both by 
primary and secondary fracture, and, as objects for de- 
ductive information, should usually be avoided. 

The choice of buildings best suited for observation in 
an earthquake region, will have been discerned from what 
has been stated, though much must always depend upon 
the observational power and shaii)ness of the observer, 
and something upon prior experience (acquirable, however, 
in a very few days' work). Buildings of the simplest 
character, large, well-built, not too much injured, and car- 
dinal, are the most important points. 

There are many detached objects the observation of 
which can afford valuable results, in reference to the path 
of the wave and the direction of its transit, besides the 
dislocations of the shell of buildings ; such as the swing 
of lamps or candelabi-a, of hung pictures, &c., and of 
twisted objects, such as vases, obelisks, &c., which, how- 
ever, do not demand detailed consideration in this place. 
Several examples occur in Part II. 



CHAPTER XV. 



TRANSIT VELOCITY OF THE WAVE FORM. 



Before passing to the subject of velocity of the wave^ a 
few remarks should be made as to the methods of ascer- 
taining its transit velocity. The transit velocity — that 
with which the form of the wave is transferred from point 
to point of the shaken surface — is so great that it can only 
be ascertained with the desirable precision, by means of 
a proper seismometer, of the self-registering class described 
in the author's fourth Report on the Facts of Earthquakes, 
(* Trans. British Association,' 1858), to be established prior 
to the shock ; and the only known method of determination 
is based upon observation of the time of arrival of the 
wave, at each of three or more distant stations, within the 
shaken area. 

In the facts which we can usually collect in the field, 
after the shock, we are limited to the casual observation 
by the ordinary time measurers (clocks and watches) of the 
moment of observed shock at several places. 

Such observations are liable to multiplied sources of 
error ; from errors in the indicated local time as shown by 
the time-pieces themselves, and errors of observation of the 
moment of true shock, as said to have been recorded by 



122 SCHMIDTS METHOD. 

them, as well as ambiguous or doubtful statements; so 
that out of a considerable number of such time-facts, ob- 
tained in a seismic-shaken country, probably not above 
two or three can be really relied upon. Were we in pos- 
session of a large number of time records of considerable 
accuracy, such even as rated chronometers at the distant 
stations but still more, self-registering instruments, would 
aflford, it would then be important to apply the method of 
least squares to their discussion, in the way that has been 
done by Dr. Julius Schmidt, astronomer at Bonn, to the 
Rhenish earthquake of 1846 (*Das Erdbeben vom 29 July 

1846, imReingebiet,' &c., von Dr. Jacob N(5ggerath. Bonn, 

1847. Pamphlet, 4to). 

If we denote by a j8 7 v the surface distances in 

geographical miles from the seismic 
vertical = Z, 

/i /i' /i" /A** their respective difiFerences of longitude 

in time from Z, 

t f t" / " the observed times at A B C . . . . N, 

T, the moment that the wave reaches the 

surface at the seismic vertical Z, 

T t' t" t" the transit periods or times of running 

over the distances a j8 7 . . . . »/, 
it is obvious that 

T = t ± M - T 

and 

t"= r ± m"-t (I.) 

and that 

For places situated to the west of 

the seismic vertical T = ^ + /i — T (II.) 



TRANSIT VELOCITY OF SECONDARY IMPORTANCE. 123 

And for those to the east of the same t = ^ — /u — T (III.) 
While for those to the north or 

south of the seismic vertical or 

in the same meridian with it . . t = ^ — T . . . (IV.) 
And the respective velocities therefore 

a fi y 



' _/' _// 



-z- ' • (V.) 



Obtaining an average transit time per second for three 
adjacent places, situated in one radius of surface, from the 
seismic vertical, Dr. Schmidt then applies the method 
of least squares to the discussion of all the remainder, and 
with a result undoubtedly important, where, as in his 
example, he has had thirty distinct observations of time, 
at as many diflFerent stations ; but which, when the number 
of stations is very limited in which any real confidence can 
be reposed, possesses no advantage over a simple choice 
from the whole of the most trustworthy, and the reduction 
from these of the mean.* 

The question of transit velocity, however, although of 
great physical interest, and destined, no doubt, ultimjitely 
to connect itself in an important way with that of the 
velocity of the wave particle (or wave itself), is, as 
respects seismometry viewed as a branch of physical geo- 
logy, of subordinate importance at present. 

* Or, as suggested to me by Dr. Bobinson, giving each observation a 
weight proportional to the length of its own wave-path, which gives 
the formula — 

ar-f /3/+yr"<fec. 
or, what is the same in result, though perhaps more convenient — 

__ar4-/3r' + &c. 



CHAPTER XVr. 

SECOND CLASS OF DETERMINANTS, OBJECTS OVERTURNED, 

OR PROJECTED BY SHOCK. 



I THEREFORE poss at once to the second class of seismo- 
metric determinants — viz., those derivable from the over- 
turning or projection of objects by the shock ; i. e. by the 
velocity impressed upon them by the wave itself, and in 
the direction, of its line of transit, or contrary to it; 
taking in also, such work of fracture, as may occur in de- 
taching them from their contacts. 

And here, as the conditions of ohservaiion are very 
simple, being limited chiefly, to the accurate measurements 
of two ordinates and an azimuth, and to some considera- 
tions as to the forms of the bodies, and of their points of 
attachment, and to the mutual relations of these, we may 
avoid that prolix detail, which was unavoidable in treating 
of the deductions, as to direction from fissures and fractures. 

Cap. a. — Bodies Overthrown only, i. e. without 
Fracture or Adhesion overcome. 

I. By Horizontal Force (Normal Wave). 

From what has been already stated as to the eflFects of 
inertia in masses exposed to shock, it is obvious that any 



OVERTHROWN SOLID. 125 

loose body, so circumstanced with reference to form and 
base, as to be overthrown by an earthquake shock (i. e. by a 
simple impulse), may be regarded as a compound pen- 
dulum. As the force of the inertia of motion is always 
F = MV, and for the same body proportionate to V 
simply, so the body may be considered as if struck at 
its centre of gravity by another body (without loss of 
vis vivd by impact, &c,) of a weight equal to its own, and 
moving with an horizontal velocity = V. We exclude 
from investigation, bodies of wholly irregular figure, as 
such are not fitted for observation, and limit ourselves 
to such regular forms — prisms, cylinders, pyramids, &c. — 
as are found in connection with architectural structures 
or civil life, and are adapted for seismometry. 

In order to upset the body, the horizontal velocity im- 
pressed by the shock (whatever be the duration of the 
latter) must be suflBcient to make it turn upon one of the 
arris's or angles of its base, through an angle <^ formed 

by the line. Fig. 93, joining the centre of -. m 

gravity with that angle or arris, and the ver- 
tical through it. 

Let a denote the distance (in feet) of this 
point or edge from the centre of gravity, then 

Fur 93. 

the statical work done in upsetting the body, 
whose weight is W 

W a ( 1 — cos <l>). 

This must equal the dynamical work acquired, which (as 
is well known), is equal to the work stored up in the centre of 
gyration^ or — 

Wa(l-cos<^) = 

^9 




126 SOLID CUBIC BLOCK. 

where « is the angular velocity of the body at starting, 
k the radius of gyration, with respect to the point or arris 
on which it turns, and g the velocity acquired by a falling 
body in one second of time. 

Equating these two values of the work done we find 

co^k^ = 2ga (1 ^ COS ip) (I.) 

but ft), the angular velocity, is equal to the statical couple 

applied, divided by the moment of inertia, or 

Fa cos <4 
ft) = — — — 

sqaaring and substituting 

a cos^i^ 

and since the length of the corresponding simple pendvlum is 

/=- 
a 

In order to apply this formula to any given case we must 
determine the corresponding value of /, the simple pen- 
dulum applying to that case. 



Fig. 94. 

1st In the case of a solid cube overturned (Fig. 94) 
whose side is a ; 



F = 



2-^ 



a 

y/2 



SOLED PARALLELOPIPED. 



127 



therefore 



and 



■" a "" 3 



cos <A = — T=: 

V2 



substituting these values in (11.) we find 

^'=|5'a (a/2-1) 



(III.) 



and the following geometrical construction is obtained 
from this expression. 

Let 5 = the diflFerence between the diameter and side of 
the cube = a {y/ 2—1) 

F'=2^x (1^) av.) 

Or, the height due to the horizontal velocity of the wave 
of shock is equal to four thirds of the diflference of the 
diameter and side of the cube. 



// . /' s 



) 




Pig. 95. 



2nd. In the case of a solid rectangular paralMopiped 
overturned (Fig. 95). 
The altitude being = a, side of the base = /8, and 

tan <^ = -, we have 



F = 



a« + /3» 



a= i^/a« + fl» 



128 COLUMN OVERTURNED. 



therefore 



^=- = fV«^ + ^ 



substituting in (Eq. II.) we find 



I — cos (^ 



or, 

a' + ^ 



V'=^gx — — ^ X (V«' + iS* - a). (VI.) 

Let S, as before, denote the diflTerence between the 
diagonal and altitude of the parallclopiped, 



5= ^«« + /8*- 



a 



a^ + IS" 

and since — = sec^ <^ 

a 

we have the following resulting theorem — 

** The height due to the horizontal velocity of wave that 
will overturn a rectangular parallclopiped is two thirds of 
the diCTcrence of the diagonal and altitude, multiplied by 
the square, of the ratio of the diagonal to the altitude, or of 
the secant of the angle <^." 

3rd. In the case of a solicl right cyliyider overturned. 

The height of the cylinder, or altitude, being a^ and the 
diameter, or base, j8, as before, we have 



and 



therefore 



15^+ 16 a^ 

" 48" 



^ ^_ r5|8' + 16a^ 



HOLLOW SQUARE BUILDINGS. 



substituting in (Eq. !!•) and since 



129 



cos* <^ = 



a' + ^ 



^ = 12-;5 — x^v/^' + iS'O-cosi^) (VIL) 



•^ 


» 


g 


L^ 



Fig. 96. 



4th. In the case of a hollow rectangiUar ptrcUlelopiped 
overturned (Fig. 96). 

Let the edges of the parallelopiped be a, jS, 7, the thick- 
ness of its walls being small in relation to their lengths, 
and suppose it overturned round the edge or axis y. 

It is easily demonstrable that 

2 /8 (g* + /ffl) + y (2 g* + 3 /ffl ) 
6 (/8 + 7) 
and 



a = i>v/g* + i8» 



3ind therefore 



F 2 /8 (g* + /3^) + 7 (2 g* + 3 ^) 



a 



3{P + y)^a^ + 0^ 



(VIII.) 



from which, substituting the value of / in Eq. II., and 

13 
remembering that tan <^ = — we obtain F, the horizontal 

velocity. 

VOL. I. K 



130 



HOLLOW ROUND BUILDINGS. 



5 th. In the case of a hoUow cylinder overturned 
(Fig. 97). 



* >9 • 




Fig. 97. 

Let the altitude of the right circular cylinder be a, the 
exterior and interior diameters of its base /8, jS', so that the 

thickness of the wall = — r — 

It 

then 



F = 



15 /y + 16 g' + 3 jS^^ 
48 



which is the case of the solid cylinder when jS' = 0, and 
when the thickness of the wall is so small in relation to 
the other dimensions that it may be neglected 

9 /3' + 8 a^ 



k^ = 



24 



In either case, the distance of the centre of gravity from 
the axis or point of rotation at the base is 



>2 



Hence, in the first case, 

P _ 15 ^^ + 16 a» + 3 /3" 

a 
and ia the second case. 



24 V«' +/3' 



(IX:) 



• • • * • 



and 



F_ 9 ^^ + 8 g" 



^-, ^ 9 /3' + 8 a^ 1 - COS ii> 



(X.) 



12 ^a* 4-/3= 



COS* ^ 



WEDGES SEVERED OFF. 



6th. In the case of a soUd paraUehpiped with two 
adherent wedges, overturned ronnd the free or 
exterual arris. 

This form Is that frequently occurring, as thrown from 
the ends of rectangular buildings, and described in treating 
of fissures, the end wall being the parallelepiped, and the 
wedges the adherent portions of masonry, fractured from the 
side walls. 

The general and exact treatment of this case involves 
expressions too complex for practical use. The case should 
never be appealed to for deciding the value of V, unless 
the magnitude of the parallelopiped be large, in proportion 
to that of the wedges, the lower at^le of the latter 
small, and not very unequal at the two ends of the paral- 
lelopiped, and the thickness of the walls ft small in 
proportion to the height a. In that case a sufficiently near 
approximation is readily made. 

Referring to Fig, 98, let the mass of the two wedges 




be determined, and reduced to a parallelopiped, two of 
whose sides shall be equal to a and y, these being the 



132 WEDGES FROM QUOINS. 

height and length of the parallelopiped, overturning 
on 7. 

Let the tliickness or third dimension of this rectangular 
plate be t, and let it be supposed applied to that side of the 
parallelopiped, to which the wedges were adherent, and 
added to the thickness t^ or width of base of the paral- 
lelopiped, for the value of fi = t + t. Further, h being the 
height of the end wall or parallelopiped, let its altitude 
be assumed increased in the proportion 

t : h :: i + ^ T : a 

for the new value of a. The case now resolves itself into 
that of Eqs. V. and VI., substituting in these the new 
values of a and /8, thus obtained; in any case worth 
practical application this may be done without sensible 
error. 

Case 7th. Angular wedge thrown over upon its apex. 

This is the case referred to pp. 66-72, in treating of 
fissures, as one of frequent occurrence, and valuable 
in deciding direction of wave-path. It can, however, 
be very nearly applied to the determination of velocity. 
The problem, generally treated, leads to very complex 
results ; and approximations are equally tedious, except in 
the case in which the direction of the wave-path is parallel 
to one of the external sides of the wedge, when the wedge 
vanishes and the case becomes identical with the last 
one. 

What has preceded refers only to horizontal force or 
velocity V (normal wave). We now proceed to 



OBUyUB FORCES. 133 

II. Oblique Force {Svbn&rmal, Abnormal, and Sub- 

abnormcd Waves). 
Let O' be the wave-path passing through any build- 
ing whatever, as Fig. 99. 




Fig. 99. 

Let O X be perpendicular to the lines O Z and Y, 
and let «, /3, and y be the angles made by O'O, with 
OX..OY..OZ. 

IfV = the total velocity, or that in the path of the 
wave, and r, v^ v. the components along X Y and Z, then 
Wj, = V cos a 

7., = V cos ^ (XL) 

y, = V cos 7 

The effect of w, in overturning the structure has been 
already considered. The component v, produces no direct 
effect in overturning, although its action parallel to Y may 
fracture and disintegrate the building. 

If the structure is capable of being overturned in the 
plane of Y Z, and also in the plane of X Z, the components 
V, and v, miist act together, and compel it to turn round 
upon one of the extreme points in the line O Y. In that 
case, the motion ceases to be comparable with that of a 
compound pendulum, and is reduced to the movement of 



CENTRE OF GRAVITY WITHIN 



a body round a fixed poiat under the inflaence of gravity ; 
one which, even in its simplest cases, would be too difficult 
of reduction for practical purposes, and which virtually 
never occurs in seismometric observation. If, therefore, 
the force of the wave be confined to the plane X Z, and be 
emergent at an angle e with the horizon, we have 



v^= V cos e 
V, = V sin e , 



(XII.) 



It being remarked that when the wave is not strictly sub- 
normal, we may always view it as such in the first instance, 
and resolve the valne of V found, through the abnormal 
angle, the latter being less than sufficient for longitudinal 
disintegration of the wall or structure. 

The general case of the subnormal wave must be dis- 
tinguished into two. First, when the wave*path through 
the centre of gravity falls icithin the base, second, when 
it falls without the base of the structure. 

Let O'o'C (Fig. 100) be the wave-path emergent 
within the base. The structure is urged by inertia against 
the ground in the direction CO' 
(contrary to the wave in its first 
semiphase), aud it cannot be ove^ 
turned by that movement of the 
wave at any velocity, (that is, by 
the direct shock) ; but it may be 
overturned by the wave in its second 
semiphase (or by the return shock). 
Fig. 100. jjig ijmn Qf ^jjjg^ ig ^iiere the wave- 

path, passes through the centre of gravity and the arris of 
the base, round which the structure should turn, when it 




AND WITHOUT THE BASE. 



136 



is stm capable of being overturned by the first semiphase 
of the wave. 

In either case, overthrow by the second semiphase, 
although mechanically possible, seldom occurs (for the same 
object), in parts of buildings, as some support or obstacle 
generally props it against the latter. 

Let a body cylindrical or prismatic be overturned by a 
wave in the path C (Fig. 101). Inertia of motion, due to 




Fig. 102. 



the jir^ semiphase^ acting in the contrary direction C 0, 
tends to make the structure turn round the axis A. 
The overturning couple is 



where a and j8 are double the co-ordinates of the centre 
of gravity, or, M being the mass, 

MV (a cos ^ — j3 sin e) 
2 

Dividing this by the moment of inertia, we obtain 

V (a cos ^ — |3 sin e) 



O) = 



2 1^ 



136 BOOB SEUFHJkSESu 

SahstiQitiDg this expreaaoD in Eq. L, we find 

V = z ^^—T-' ? X (1 - cos ^) 

bat 

\ (acos^ — ^sin^)=/=aco6(^ + 
or 

^' = 2 </ / X ^r;^'^^ . . . (xm.) 

cos" (^ + «-) ^ ^ 

Which, when e = 0, redaces itself to Eq. II. for the normal 
wave, or F' = Y \ 

Bnt if the stractnre be ocertumed hy the second send- 
phase J inertia acts in the direction of transit O C, and tends 
to make it oyertnm ronnd the axis R 

The oyertnming conple is 

M V (tt €06 e + /3 sin e) 
2 
and 

., a cos d + fj sin e , , 

/' = 2^ = a cos (<^ - £?) 

/ in the former, and/' in the latter cases, denoting the per- 
pendiculars let fall upon the wave-path from the axes 
A and B respectively. 

Substituting in Eq. I., as before, we find 

T»=2<y/x \" "^ ^, . . . (XIV.) 

cos' (<^ — 

When e = or the wave normal, this also reduces to 
Y^{. XL, as must necessarily result from the fact that both 
semiphases of the wave (assuming the velocity practically 
the Stune in both) are equally efiective in producing over- 



THREE CASES. 137 

throw by horizontal shock ; the structure presenting similar 
aspects to the wave-path, in both semiphases. 

When (f> + e = 90°, the wave-path passes through the 
centre of gravity and axis of overturning, and V becomes 
infinite, so that the structure cannot be overturned by any 
velocity of shock during the first semiphase of the wave. 

When e = 90°, and <^ = 0, the wave-path is vertical, 
and the structure cannot be overthrown in the wave-path 
by any velocity, but may be conceived liftedj in the second 
semiphase of the wave, by its own inertia of motion first 
impressed. 

And when <^ — e = 0, the wave-path is perpendicular to 
the diagonal, or/' = a, and the wave in its second semi- 
phase, produces its maximum effect, that maximum in 
the first semiphase, of course occurring when the wave is 
normal. 

Proceeding to the consideration of the special problems: — 

8th. In the case of a solid cube overturned by sub- 
normal wave. 

Preserving the foregoing notation, the structure shall 
overturn round A (Fig, 102), in the first semiphase, or 
round B in the second semiphase, of the wave, 

a being the side of the cube, 

and since <f> = 45° (Eq. XIIL and XIV.) become 

COS ^ (4o ±e) ^ ' 
the sign + applying to the first and — to the second semi- 
phase of the wave. 



138 PARTICULAB PROBLEMS. 

9th. In the case of a solid paraUelqpiped overturned 
{subnormal loave). 

Here 

l = %y/a^ + ^ 

therefore 

cos* {^ ± e) ^ ^ 
the signs + and — being attended to as before.* 

10th. In the case of a solid right cylinder overturned 
{subnormal team) . 

In this case 

15 /g* + 16 g* 

and 

V. = ^ lifi±^ X -^-^ (XVII.) 

12 ^/a^ + pr COS* (<^ ± ^) ^ ^ 

+ and — applying as before. 

11th. In the case of a hollow paraUelopiped- over- 
turned {subnormal wave) . 

Here, from Eq. VIII., XIIL, and XIV., we have 

2^ 2 iS (a^ + ^) + y(2«* + 3j3^) 1 - cos <^ 



O + 7) \/ «' + iS" cos\ii>±e) 

(XVIII.) 



♦ Eq. XVI. has been applied in the text of Part II. under the form 

V* = i i7 X T- V--7;^/^- . X (1 - cos 0) 
(a cos « + /i sm e)' ^^ 



FRACTURE. 139 

12th. In the case of a hollow right cylinder over^ 
turned (subnormal uxive). 

Here, from what has preceded, we have 

12 ^ x/a' + $' ^ cos" {<f> ± e) ' ^ -^ 

Proceeding now to 

Cap. B. — Bodies or Structures Fractured. 

If the fracturing force, or M V, in the direction of the 
wave-path, M being the mass broken off, act transversely 
to the plane of fracture, the case is one simply of co- 
hesion destroyed by an impulsive force, in which 2 M V is 
equal to the statical strain that would have produced the 
same fracture ; and if the direction of the force be such as 
to produce rotation in the mass fractured oflF, there will be 
a dynamic couple to be taken into account ; and lastly, if 
the plane of fracture occur so, that it is not transverse to 
the line of force, the latter may be resolved into one that 
shall be so, which is all that need be said as to direct frac- 
tures^ such as those passing down vertically or diagonally, 
as fissures through walls, &c. ; and the rather because, 
precious as these become as indices of direction^ they should 
never be adopted as measures of wave-velocity, from the 
uncertainty that must always attend the knowledge of the 
coeflBcient of force necessary to produce fracture through 
the joints across the beds of masonry, &c. 

Proceeding, therefore, to the determination of fracture 
occurring at the base^ or in horizontal planes, or in those of 



140 PRACTUBE AT BASE— NORMAL WAVE. 

the continuous beds of the masonry, or tfaroagh homogeneous 
bodies, such as stone shafts of columns, Ac. — to none of 
which the same uncertainty of coefficient applies — 

First. Let the wave-path be normal (the force hori- 
zontal). 
If any prismatic or cylindrical (Fig. 103) solid strno- 
tore be broken off, by an horizontal fracture at its base, 
from its own material below that base, and by a normal 
wave, neither turning over, nor being displaced, but tend- 
ing to overturn, upon the axis of A, by 
the first semiphase, and upon that of B, 
by the second semiphase of the wave. 

The condition for its fracture thus, 
withotU overthrow, is that the overturning 
moment, shall be equal to the moment of 
' "° cohesion of the fractured surface of the base. 

The fracturing force may be considered as applied at 
the centre of gravity of the mass detached ; and the 
moment of cohesion at half the radius of oscillation of the 
plane of fracture, at the base, viewed as surface about to 
vibrate round the axis A or B, as a compound pendulum.* 




* It has been remarked that "this involves the asaumptions, (1) 
that the body will begin to revolve as if it were absolutdjf rigid, 
and (2) that the force of adhesion, on any element of the plane of 
fracture, will vary, caUris paribus, as its distance from the axis A, aa if 
the force were not impiilsive, but the mass had extensffi3ity ; and it is 
asked, is there any oxperimeatat law which sanctions this conolusion 
for impulsive as well as continuouB forces? If the mass has KCtan* 
sibtlity in its elements perpendicular to the plane of severance, it must, 
in like manner, have compressibility ; and in such case tlie mass wilt not 
tend to turn round the axis through A. but ronnd some axis parallel to 
it, on one side of which, Ihero will be compression, and on the other 



MODULUS OP DYNAMIC COHESION. 141 

In accordance with the theory of Leibnitz, we therefore have 

Mr/=FA|; 

M = being the mass of the detached portion ; 
V = the velocity of the wave in its path (normal), 
/ = the perpendicular height of the centre of gravity 

above the base of fracture ; 
F = the coefficient of dynamic cohesion, or the force upon the 

unit of surface of the material fractured, which, when 

suddenly applied, is sufficient to produce fracture ; 
A = the area of the base of fracture in such units ; 
k = the radius of gyration of the plane of fracture with 

respect to the axis A or B. 
i8 = the width of A B. 

If W = the weight of the mass broken oflF, g = the 
velocity due to gravity in one second, then 

FA F 
and if the detached mass be any regular prism or right 



extension. If the compressions and extensions follow the same law, 
and have the same coefficient, this axis, or neutral lim^ will divide the 
base into two equal parts, which would entirely change the necessary 
amount of the fracturing force." I should admit the correctness of the 
conclusion thus expressed, if I could altogether, the premises, and their 
applicability to the matter in hand may be disposed of in a few words. 
The actuid extensibility of all building materials, and still more their 
compressibility, are so extremely small, that for our present purposes 
both may be regarded as in the text, without sensible error, the com- 
pressibility for the small intensity of pressures we are dealing with is 
insensible, and therefore the position of the axis of rotation is prac- 
tically that assigned to it. If the objector will point out any good 
ground for adopting any other axis of rotation, I shall be ready to 
employ it. 



TX-» 



>PECL1L PB0BLE3IS. 



erlmder. whaee heighc skbove the iiorizoatad plane of frac- 
tnre is «• thea r = - . If L be die modulus of dynamic 

'ZohdMon — a i:i>?fficieEi: represenring the length of a prism 
of the Tozne m;iremL whose weight t? eqnal to the forte 
upon the anit of foplace, if saddealT applied, which is 
sofficienc to tear it direetly asonder, — then 



or 



r LP 



(XXI.) 



(xxn.) 



1st. 



Here 



In the case of a *>&/ eubey fractured frain its 

hcrisofital base. 



a' SP 



therefore 



r ^ LI 



or 



J 



r=214»> - 

a 



(XXIII.) 



2nd. In the case of a solid parallelopiped^ fractured 
from its horizontal base. 



fif'n? 



therefore 



or 



ir — 


• 


o a 




»«..... 


r 

F= 21.46^ 





(XXIV.) 



VARIOUS FORMS OF BUILDING. 



143 



3r4 In the case of a right circular solid cylinder, 
fractured from its horizontal base. 
Here i8 = D, the diameter of the cylinder, 



^ = T^ iS' 5 



therefore 



''=f*x?i#,' 



or 



F= 20-12 



LD 



O 



(XXV.) 



J 



4th. In the case of a hollow paraUelopiped, fractured 
from its horizontal base. 

Assuming the thickness of the walls small^ as before, 
and 7 being that side of the parallelopiped, which is the 
axis of inceptive rotation. 



4(^ + 7) ' 



therefore 



V=hg% 



L jQ (/3 + 2 y) 



or 



V = 16-10 X 



L /8 (|8 + 2 7) 
«' (^ + y) 



(XXTI.) 



5th. In the case of a hollow square prismatic tower, 
fractured from its base. 

Then, j8 = 7, and (Eq. XXVI.) becomes 

Li8 



V=ig>c 



a 



a » 



or 



V = 24-15 X 



L^ 



(XXVII.) 



o 



144 



SUBNORMAL WAVE. 



6th. In the case of a hollow right cyUnder^ fractured 
from its hose. 



Here 



F = 



5 jffl + )8^^ 
16 ' 



and 



r=^x^^'^^"^^ 



or 



8 



F= 4-02 X 



(5 D^ + D^^) L 



> 



(XXVIII.) 



In the 5th and 6th cases, and generally in cases of solid 
columns or minarets, &c., or hollow prismatic or cylindrical 
towers, the fracture at the base, is never perfectly, and all 
through, horizontal. When the breadth or diameter is 
small, however, in proportion to the height, the irregularity 
of the fracture is not great, and the slope from horizontal 
also small; and no serious error is introduced by con- 
sidering the plane of fracture as horizontal 



Secondly. The wave-path subnormal {farce 
emergent and oblique to the horizon). 

When the wave-path is subnormal, in any prismatic 
structure, the first and second semiphases of the wave, act 
upon it as already explained ; the former to produce in- 
ceptive overturn upon the axis (arris of the base) A, and 
the latter upon the axis B. 

Both cases are included in Eq. XXI, 

L " 



/^ 



Writing for / = the perpendicular height of the centre of 



VARIOUS FORMS OP BUILDING. 



145 



gravity above the base of fracture, as in the preceding 




/J x^ 



Fig. 104. 



equations,/ or /' of Fig. 104, and Equations XII., XIIL, 
&C., &c., in which 

/ = a cos (<^ + ^) 

/' = a cos (<^ — e) 
and a, as before, the distance of the centre of gravity from 
the axes of inceptive rotation, we have 

V = (/ X J^ X sec (<^ ± ^) (XXIX.) 

The sign + applying to the first semiphase, and that — to 
the second semiphase of the wave. 

7th, In the case of a solid cube, fractured from its 
horizontal base^ by subnormal xjoave. 

Substituting for J^ its value, and also for a, 

3 3 



a = 



\/2 



we obtain 



V = 



= '^^ ^ X - X sec (45'' ± e) 

3 a 



or 



V = 15-17 X - X sec (45° ± e) 

a 



. . (XXX.) 



VOL. I. 



146 



VARIOUS POBMB CONTINUED. 



8th. In the case of a solid paraUdopipedj fractured 
from its horizontal base, by subnormal toave. 



Here 



P = - 
^ 3 



a = ^ a sec ^ 

and substituting in Eq. XXIX., we find 

cos <^ 



XT 2 L^ 



o? COS (<^ ± e) 



or 



V = 21-46 —^ X 



cos <^ 



COS (<^ ± e) 



(XXXI.) 



9 th, In the case of a right circular solid cylinder^ frac- 
tured from its horizontal basCj by subnormal wave. 



Here 



*" = re^ 



a = ^ a sec <f> 



therefore 



17 5 ^^ 



cos <f> 



a^ cos (<^ ± e) 



or 



V = 20-12 ^ X 



cos <f> 



a^ COS (<^ ± e) 



(xxxn.) 



lOth. In the case of a hollow parallelapiped, fractured 
from its horizontal base^ by subnormal wave. 

Substituting for ^ and a their values 



k? = 



4 (^ + 7) 
a =: i a sec <^, 



TOTAL VELOCITY— FRACTUEE AND OVERTURNING. 147 



we have 
V = i^r X — rhr- — r^ X 



cos <f} 



or 



«' (i8 + 7) cos (<^ ± ^) 



cos (f> 



(XXXIII.) 



V = 1610 X t^^^ii^ X - ,,,, 

« (iS + ?) cos(<^±e) 



11th. In the case of a hollow square prismatic tower ^ 
fractured from its horizontal base^ by svimormul 
wave. 
As before, /8 = 7, and 

cos <f> 



V = |^x^/-x 



c? COS (<^ ± e) 



or 



T fi 

V = 24-16 X — ^ X 



cos <^ 



a^ cos (<^ ± ^) 



. . (XXXIV.) 



12th. In the case of a hollow right cylinder, fractured 
from its horizontal base, by subnormal wat^. 



Here 



A^ = 



&^ + P" 



therefore 



16 
a = ^ a sec (f) ; 



^ = ^ff^ ^^8 ^ 



COS (f> 
COS (<^ ± ^) 



or 



V = 4-02 X — '^ i"^ X 

a U 



COS <^ 



COS (<^ ± e) 



(XXXV.) 



Thirdly. Let the stracture be fractured, from its 
horizontal base, and also overturned, whether by 
a normal or a subnormal wave. 

If the stracture be observed fractured only, at the base, 

l2 



143 FRACTURE, OVERTURNING AND PROJECTION. 

but not overthrown, the velocity impressed was sensibly no 
more than sufficient for fracture ; if it be overthrown also, 
it was sufficient for both. Hence, if ty = the velocity 
determined by the Eq. XXI. to XXXV. for ftucture only, 
and v^ = that for overturning only, by the Eq. I. to XX., 
the total velocity of the wave will be found 

Y = Vf + v, (XXXYI.) 

It may occur, that a structure shall be fiuctured from 
its base, but not overturned, (merely caused to osciUate 
within narrow limits), by the first semiphase of the 
wave; and being so broken, may be overturned in the 
direction of wave-transit, by the second semiphase; in 
such an example (which is of rare occurrence) the change 
of sign, in the second members of the equation, must be 
attended to, and also whether the proper velocity of the 
mass, viewed as a pendulum, in returning back upon its 
base, may have conspired with the velocity of the wave 
itself, in its second semiphase, to overturn the body. In 
such an example, if the wave be subnormal, with a pretty 
large angle (^), the impressed velocity will generally be 
found sufficient, to have projected the structure (if falling 
entire) to some distance from its base, as well as to have 
overturned it. 



CHAPTER XVII. 

VALUES OF THE COEFFICIENT L. 



Before concluding this section, it remains to assign the 
values of the coefficient L for practical use. 

It consists of two factors : the tenacity or resistance to 
rupture, by a force suddenly applied; and the specific 
gravity of the mass fractured ofiF, by direct pull from an 
unit of section. 

When a direct force, producing fiucture by extension, is 
gradually applied to any prism, whose length and section are 
both unity, the work necessary to produce the rupture is 

w=ip/ (a.) 

P being the static load gradually applied, and I the 
amount of extension of the body on the unit of length 
at the limit of rupture. But if P be applied at once 
(suddenly), then 2 W = P /, the accumulated work, is 

P 

twice that necessary for fracture, or — = the force, 

whose tension mddenly applied^ as by an earthquake shock, 
shall rupture the prism. 

This force we suppose applied by the weight of a prism 
of the material fractured, whose base is the unit of section 
fractured ; or 5 being the specific gravity 

L = X5 = ? (38) 



150 FRACTURE IN WALLS OCCURS AT JOINTS. 

When the question relates to the fracture of a homogeneous 
body — such as a column shaft, of one block of stone for ex- 
ample — ^then the force P to be taken, is that which applies 
to the material, and S its sp. gr. But when the fracture 
occurs in walls of whatever sort, it takes place by the 
giving way, by loss of adhesion (generally), or sometimes 
of its own cohesion, of the mortar or other cement, as being 
the weakest part of the heterogeneous mass : in which case, 
P is to be taken for the rupturing force of either the 
adhesion or cohesion (as the case may be) of the mortar 
or cement, and S the specific gravity due to the whole mass 
of masonry. 

Fracture seldom or never occurs through the solid stone, 
in masonry, but always at the mortar joints, and generally 
by their loss of adhesion, to the stone at the fiBu^es of the 
joint. It rarely occurs through the brick, in brickwork, 
and only when the cohesion of the brick itself, is less than 
that of the cement. 

To enable these equations to be applied generally, in 
earthquake countries, I have arranged the two following 
tables, I. and II., which embrace almost all the reliable 
information we as yet have, applicable to the matter, and 
from which, the value of L may be deduced, for a great 
variety of cases. 

Many of the numbers, for want of better experimental 
data, can only be viewed as approximative. 

The most important numbers by far, are those relating to 
the adhesion and cohesion, of the varieties of common 
mortar; and, fortunately, these have been ascertained 
by Boistard, Gauthey, Treussart, and Colonel Totten, 
with considerable accuracy. 



TABLE OF FACTORS FOR COEFFICIENT. 



151 



The use of the coeffident L, in Eq. XXI. et seq., con- 
siders the value of I (Eq. SI) evanescent, so that the prism 
at the moment of fracture has not risen through an appre- 
ciable angle, at the surface of fracture, and from the ex- 
tremely small extensibility of mortar, stones, &C., this is 
suflSciently true to nature. 

Table I. 
Factors for the coefficient L^ 



Material. 



Limestone, Gaserta, Naples .. 
Upper Limestone, Genoa 
Jurassic Limestone, Giviy 
Cretaceous Limestone (Gom- 

peigne) 

Lava, Hard Yesuvian 
Lava, Soft Yesuvian 
Lava, Pipemo (Pozzuoli) 
Travertine, Old Roman .. 
Tiavertino, Paastum 

Peperino, Boman 

T11&, Old Boman 

Tu£s^ Naples 

Hard brick 

Soft ill-burnt brick 

Mortar, lime, and sand, un- 

ground 

Ditto, ditto, ground 

Mortar, Pozzolano, of Home 

and Naples, unground .. 

Ditto, ditto, ground 

Mortar, Old Koman (Gampagna) 
Mortar, Old French (BastUe) 
Plaster of Paris (mean) .. 



1. 

Weight 

in 

pounds 

percnh 

foot 

Sp.gr. 



170 
169 
148 

164 

166 

107 

162 

147 

141 

123 

78 

82 

98 

91 

102 
119 

92 

105 

97 

94 



2. 

Ponnds 

per square 

ineb. 

Resistance 

to 
Pressure. 



8173 
4917 
4232 

3007 
8735 
2209 
8140 
2297 
3102 
3135 
797 
718 
1851 
1200 

423 
577 

503 
732 
1047 
753 
500 



3. 

Ponnds 

per square 

inch. 

Resistance 

to 

Tension. 



908 
546 
496 

334 
972 
246 
905 
255 
345 
347 
89 
80 
206 
133 

47 
64 

56 
81 
105 
84 
55 



4. 

Anthority 

for 
land 2. 



Bondelet 
Oauthey 

Bondelet 



Laisne 



It appears, from the few experiments that have been 
made, that the resistance of stones, &c., to tension, varies 
from ith to ^th the resistance of the same material to 



152 



SECOND TABLE OF FACTORS. 



compression. The third column is here calculated on the 

mean of such data. It cannot be •viewed as more than 

an approximation, except in the cases of mortars, which 

are from actual experiment, as given by Guuthey Q Sur la 

Construction des Pouts'), and by Bondelet (*L'Art de 
Batir'). 



• 


Table II. 








Of the specific gravities, cohesiou, and mutual adhesion, of various 


building materials. 


Factors for the coefficient L. 






Weight per 


Besistalice to 


Adherent 






cub. foot 


Tension. 


ReHiHtance. 




Material. 








Autho- 




Specific gra- 


lbs. per square 


lbs. per 


rity. 




vity. 


inch. 


square inch 




Granite 


164 


1200? 


• • 


T. 


Granite to Portland cement 


• • 


• • 


97 


W. 


Granite to Parker's cement 


• • 


• ■ 


22 


W. 


Silurian slate 


170 


2300? 


• • 


T. 


Oolite (Portland) 


132 


270 


• • 


W. 


Oolite to Portland cement .. 


• • 


• • 


146 


W. 


Oolite to Parker's cement .. 


• ■ 


• • 


42 


W. 


Sandstone, coal measure .. 


147 


234 to 250 


• • 


T. 


Millstone grit and Portland 










cement 


• • 


•• 


76 


W. 


Sa,ndfltone (^Vhitby) and 










Portland cement .. 


• • 


. . 


57 


W. 


Kentish rag and Parker's 










cement 


• • 


• 

• • 


29 


W. 


Brick, best English 


135 


200 to 230 


• • 


• • 


Brick, inferior 


97 


40 to 80 


• • 


B. 


Unglish brick in Portland 










cement 


107 


• • 


• • 


W. 


Portland cement 


127 


400 


• • 


W. 


Parker's cement 


120 


300 


• • 


W. 


Mortar (sand 3, lime 1) 


100 to 119 


11 to 20 


9-88 


B. G. 


Green and fresh 


• • 


2 


• • 


T. T. 


Mortar, ground lime and ) 








IB. Q. 

IT. T. 

1 


tiles I 


100 to 120 


40 to 80 


5-26 


Hydraulic mortar ..J 


• • 


. . • 


• • 


Jurassic limestone to mortar 


• • 


. • 


3-80 


R. 


Brick and tile to mortar . . 


• • 

1 


• • 


8-27 

i 


R. 



Authorities. — T., Tredgold. W., White, * Trans. Inst. C. E.' 
B., Barlow. B. G., Boistard and Gauthoy, 'Const, des Pont«5.' 
T. T., Troussart and Totton. R., Rondelet. 



TABLE OF VALUES— COEFFICIENT. 



153 



In the preceding table, the cements had, in all cases, six 
months to indurate, and the mortars (except in the second 
case) from six months' to seventeen months' induration. 

Examples of very old and good, lime and sand mortar, 
may be found occasionally in gbod brickwork — such as that 
of the Roman amphitheatre at Pozzuoli, for example ; or in 
rubble masonry, where the bond of the stone with lime 
mortar is peculiarly strong, as with the oolitic building stones, 
and limestones generally, and with a few sandstones and 
porous traps, in which the adhesion, of the indurated mortar, 
becomes fully equal to its cohesion, and both rise above 
50 lbs. to the square inch, for forces suddenly applied. 

In determining the mean specific gravity, of brickwork 
and rubble masonry, the proportion of mortar, to the brick 
or stone in a given volume, may be taken at from i^th to 
f th, according to the goodness of the work. 

Table HI. 
Deduced values, under different conditions, for the coefficient L. 



\ ]. s. 



\ 



No. 



I 
2 
3 

4 

5 

6 

7 

8 

9 

10 

11 



Conditions of Fractdre. 



Apennine limestone, broken through the stone .. ..* 

Cretaceous limestone, ditto ditto 

Apennine limestone rubble masonry, of best quality, 
broken through the Joints 

Apennine limestone rubble masonry, of inferior 
quality, broken through the joints 

Apennine limestone, rubble masonry of best quality, 
mortar not indurated 

Argillaceous rubble masonry of the Murgia (Apennine 
marl rocks), best quality, with indurated mortar .. 

Best Italian or Roman brickwork in mortar 

Inferior brickwork in mortar 

Brickwork, the mortar not yet indurated 

Bubble masonry of tufa and mortar, good, with mortar 
indurated 

Bubble masonry of Travertine, or Peperino, and mor- 
tar indurated 



Value of 
L. 



225 
154 

52 

30 

3-9 

55 
63 
30 
2-5 

87 

51 



-' ^ 



154 QOBXS&yS A5D ADBJBSSm. 

These raJnes of I^ are all, for the mortar when yielding 
in eokesicm. Who. obe^red to yield m adhedonj the co- 
efficient in each case beccHnes 0*lji Iw tmekwrak and 
0i)83 Ji %x limestone. The Tahies given, are also all 
for anei^it and foQj indmated (exc^ 5 and 9) mortar; 
where the latter is mider twenty-fire years laid, the yaloe 
of L donld be takai {guam prax.) at I L in the table. 

Proceeding now to 



CHAPTER XVm. 

FOMURL^ REFERRING TO CAP. D. — BODIES OR 

STRUCTURES PROJECTED. 



Let a body, A (Fig. 105), such as the coping-stone of a 
wall, a church bell, a ball or finial, upon a tower summit, &c.. 




Kg. 105. 



Fig. 106. 



be thrown from its place by the earthquake wave in its first 
semiphase (direct shock), in the direction of wave-path C, 
and be found projected to the ground at B, in a direction 
contrary to the wave transit. It is required, if the angle 
of emergence e, of the wave-path at the place, be known, to 
determine the velocity of projection, and trice versd. The 



156 GENERAL EXPLANATION. 

body is projected downwards ihroagboat its trajectory; 
motion is imparted to it, in virtue of the grasp that its 
base had of it, by adhesion or otherwise ; and the velocity 
of projection impressed, or that which, of the total velocity 
of the wave at its moment of maximum, is eflFective in pro- 
jection, is the difiFerence, between the maximum velocity of 
the wave, and that which is destroyed by adhesion, or 
other equivalent resistances. The larger the mass the 
greater is the proportion of the total velocity eflFective. 

Were there no adhesion or equivalent resistance (as in 
the case of a ball balanced on the top of a staflf), the body 
would drop plumb or nearly so, and might be struck by the 
base (the wall in Fig. 2) in the second semiphase of the 
wave ; or if the velocity of the wave were infinite or ex- 
tremely great in relation to g, the body might, whether 
adherent or not, be displaced and replaced, without pro- 
jection. These, however, do not occur. The relation in 
nature between V and g is such, that bodies are projected 
from buildings, &c., in both semiphases of the wave, and the 
adhesion of the base is most generally of such a nature as to 
impart a movement of rotation to the body thrown, which 
is suflScient to turn it over, more or less (usually from the 
forms found either through 90° or ISC'), during its descent, 
notwithstanding its high vertical velocity downwards. 

Let the axis of y (Fig. 105), be measured downwards 
vertically, and that of x horizontally from the origin, at the 
centre of gravity of the body projected, the trajectory 
described is 

a? 
•^ 4 H cos" e ^ '/ 

11, being the height, due to the velocity of projection. 



V 

\ 



. ANGLE OP EMERGENCE OR VELOCITY OBTAINED. 157 

If b denote the height through which the centre of gravity 
has descended, to reach the ground, or the horizontal plane 
passing through the centre of gravity, when so deposited, 
and a the horizontal distance, traversed by the same centre, 
on striking the ground, then 

6 = a tan ^ + — = 1- 

4 H cos'* e 

from which the following expressions are easily deduced for 
the angle of emergence (which is alternate and equal, to 
the angle of projection) and for the velocity : 



^' = n ^-TT^—, ^ (XXXIX.) 

2 cos'' 6 (6 — a tan ^) ^ ^ 

In the second semiphase of the wave (or return shock) the * 
displaced body is thrown, not downwards, but more or less 
upwards, if projected by the inertia of motion, acquired 
from a subnormal wave. If the wave were perfectly 
normal, the projection of course would be horizontal, and 
€ =z for both semiphases. 

In the case of projection by subnormal wave, observing 
that the axis of y is measured vertically upwards, and 
that of a: horizontally, from the origin, in the centre of 
gravity of the body as before, we have for the trajectory j, r-^ 
(Fig. 106) ^^^.. - ■"^" 

y = ^ tan ^ . — -= -r— . (XL.) 

^ 4 H cos^ e ^ ^ 

and substituting in this as before 

y = - 6 
X = + a 



J 



/t 



/ 



THE SAKE GEI(»fErBICALLT. 



we find 

— b = ataae — -— - ^ - 
whence the angle of emerg«ice or of projectioD is 



TaB« = 2H±-/^H(H + t)-J 



and the velocity of i»t>jectioD 
<^3 



V = : 



(XU.) 



(XUL) 



■ 2 008* € (6 + a tan «) 
As the velocity of jHrojection by earthqnake-shock has 
been proved, by the examination of this shock of December, 
1857, to be small, and therefore H, the height dne to it, 
also small ; we can find either Y or <; geometrically, by 
the application of Prc^. Galbraith's very beantiiiil problem, 
for determining graphically, either of these quantities for a 
projectile ; and as this method may be applied by any nn- 
mathematical observer, who measures on the gronnd, the 
vertical and horizontal heights 
of a body thrown, and can nse 
a pair of compasses, it will be 
weU to transcribe it 

Let A (Fig. 107) be the top 

of any tower or other elevation 

from which a body has been 

projected. From A draw A B 

vertical and = 4 H (H being 

the height dae to the velocity, 

supposed given). Through A 

*'°*"^ draw A X horizontal. Bisect 

C B in Y, and on B C describe the semicircle B X C. 

Bisect B A in O, and with as centre and O X as radius 




VELOCITY OF PROJECTILE MAY BE LESS THAN WAVE. 159 

describe the circle X T. This is the locus circle (i. e. that 
in which the line of aim — in our case the wave-path, shall 
cut the vertical drawn through the point D, at which the 
projectile fells — whether the angle e, be above or below, 
the horizontal line through the point of projection). 

Let D be the point at which the projectile fells to the 
ground ; draw D F E vertical through its centre of gravity. 
The directions A E and A F, formed by its intersections 
with the vertical, give the superior, and inferior angles of 
elevation, for the given horizontal range and elevation, and 
coincide in result with Eq. XXXYIII. and XLI. 

The wave-path must always, be either horizontal or 
emergent. Hence in the first semiphase of the wave, al- 
though the motion of the projectile is contrart/ to that of the 
wave transit, the angle e^ given by the above construction, 
will be the superior one, and also in the second semiphase 
of the wave, in which the motion of the projectile is in the 
same direction with the wave transit, the angle e will be 
still the superior one. 

The values of V. given by Eq. XXXIX. and XLII. are 
those of the projectile itself, but are less than the maxi- 
mum velocity of the earth-wave by the velocity destroyed 
by adhesion, &c. The latter produces rotation in the 
body, and we generally find it overturned^ as well as pro- 
jected. The velocity, therefore, destroyed by adhesion is 
equal to that which has produced the rotation, Vj and may 
be arrived at by the Eq. I. to XX inclusive, and that 
velocity so found reduced to the direction of the wave- 
path, and added to the velocity of projection, will give 
the total velocity, or 

V = the maximum velocity of the wave. 



IGO EMERGENCE AND VELOCITY BOTH OBTAINED. 

If in the same locality, we are enabled to observe two 
diflFerent bodies, both projected, and to measure the vertical 
and horizontal distances to the point of fiQl, we can 
determine both the angle of emergence of the wave-path {e) 
and the maximum velocity of the wave. Thus, for example, 
let both the bodies, be projected by the second semiphase 
of the wave, and let a b and a' V denote the co-ordinates 
in X and y, of the two trajectories; then by Eq. XL. 
we have 



a' 



— 6 = a tan ^ — — _ , 

4 H cos* e 



a'^ 



— 6' = a' tan e __ 

4 H cos' e 



from which we find 



a^b'^a'^b 

^' = aa'(a'-a) (^H) 

„ , aa' (a' ^ a) 

° "" ' = 4 (aV - Ji) (^^■) 

and substituting for H its value — we find 

a a' {a! — a) 
^ =3^ 2cos'e (ab'^a'h) ^^^^') 

In the case, of the upper portion of a toall, thrown off 
from the lower which remains standing^ which is a very 
frequent one, the equations to apply, are the same as for a 
body, projected and overturned from the summit; the 
upper portion turning over first, upon one arris, and then 
being thrown more or less from the base of the wall, in a 
trajectory. 

The preceding equations embrace, probably, every case 
likely to occur to observation. 



CHAPTER XIX. 

THE PHYSICAL AND GEOLOGICAL FEATURES OP THE 

COUNTRY SHAKEN. 



Before proceeding to Part II. some remarks are required 
upon the general physical and geological features of the 
earthquake region of December, 1 857, in order that the 
references as to their modifying efiFects, upon the directions, 
local variation of intensity, reflection, &c. of the shock, to 
be made in Part III. may be understood. 

The notion commonly formed, from our books of geo- 
graphy and maps, of the physical configuration of the 
surface of Italy, is that of a long strip of land, separating 
into two at the south, and divided right down the midst of 
each strip, by the ridge of the Apennines, with a steep 
watershed to either shore. 

This is but a very inadequate representation of the facts, 
and only to a limited extent true. Confining ourselves to 
the kingdom of Naples — i. e., starting on the north, with a 
line reaching from the mouth of the Tronto on the east, to 
that of the Tiber on the western shore; fix)m Monte 
Pennine (in Boman territory) down through the summits 
of Monte Como and the Majella, to near Monte Acuto, 
south of Melfi — the highest ridges of the southern Apennine 
chain, are found following a wavy line, at about one-third 

VOL. I. M 



162 DIRECTIONS OP THE 

the breadth of the peninsula, from its northern coast. 
Again, from Monte St. Angelo, just above Amalfi, to a 
point approaching the Adriatic coast, some miles south-east 
of Bari, a transverse ridge stretches nearly west to east 
and from sea to sea, and which bending southward, to the 
north of Taranto, continues with decreasing development, 
down into the extremity of Otranto. 

Returning to Monte Acuto, the great central ridge is 
continued, in a direction almost due north and south, for 
nearly 150 miles, and then stretches in a waving line, down 
to the southern end of the Galabrian peninsula, where it 
culminates in Gocuzzo and Aspramonte. 

At the north-western end of the first ridge, we have 
Monte Corno, nearly as high as Etna in Sicily, with several 
summits, between that and Acuto, of from 7,000 to 9,000 
feet in height. In the transverse ridge, Acuto is the 
highest crest, probably ; but Monte St. Angelo, in the 
little peninsula of Cape Campanello, terminates the western 
end, as a rampart to the Bay of Naples, at an elevation of 
4,770 feet, the elevation gradually declining from Monte 
Acuto to the Adriatic. 

Again, between Monte Acuto and Capo del Armi, at 
the toe of Calabria, we have Cocuzzo, 5,620 feet, and 
Aspramonte, variously stated at from 5,830 to 4,3iB0 feet 
The little peninsula of Gkirgano forms a small mountain 
system of its own, an elevated well-studded table land, of a 
lumpy, roundish form, with radiating stream channels, in 
which Monte Calvo is said to be the highest point, reaching 
5,088 feet. 

These ridges, in lines far from straight, and broken by 
many differences of elevation, are, indeed, the spine and 



GREAT CHAINS. 163 

ribs of Southern Italy; but our notions thus limited, convey 
no true idea of the physical features of the country. These 
ridges determine, the great forms and directions of the 
water-sheds, but by no means those of the vast tracts of 
subordinate mountain ranges and culminations, by which 
these axial chains are surrounded and buttressed. 

From the Tronto, to Gargano, the lateral mountains tend 
on the whole, to stretch parallel to the lines of the rivers, 
which fall with north-eastern courses into the Adriatic; 
and hence, the lines of mountain and valley, are generally 
transverse to the axial chain on this side. 

On the opposite side, between the great axial chain and the 
transverse axis, from Naples to Monte Acato, the great 
rivers, such as the Carigliano and the Yoltumo, take in 
tributaries from every point of the compass, and indicate, 
the extreme irregularity that prevails, in the alignment of 
the secondary ridges. This is also, to a less extent, true of 
the great trapezoidal area, between Salerno and Monte 
Acuto on the north, the gulfs of Salerno and Policastro on 
the west and south, and the southern continuation of the 
axial chain from Monte Acuto on the east. The southern 
branches, however, of the largest river within this boundary, 
the Salaris or Sele, have a nearly south to north course. 
Eastward of the axial chain of Monte Acuto, and over the 
whole province of Basilicata, the rivers all run, nearly 
parallel to each other, and in a direction almost exactly from 
N.W. to S. E. into the Gulf of Taranto ; but the directions of 
the secondary ridges are, on the whole, distinctly trans- 
verse to the river courses, which make their way through 
breaks or depressions, or wind round the terminals of the 
short and abrupt ridges. So that on the whole the moun- 

M 2 



164 GREAT RIVER COURSES. 

tainous country south of the transverse axis, and down to 
the parallel of 40°, at Policastro, may be viewed largely, as 
a surface furrowed in parallel ridges, running north and 
south with a trend westward, but twisted, broken through 
by gaps, and irregular in a high degree. 

South of parallel 40°, to the extremity of Calabria 
Ultra, the lateral chains, tend to place themselves at right 
angles to the axial chain, except about the boundary 
separating the two Calabrias, between Cape Suvero, on the 
west, and Capes Alice and Colonne on the east coasts, 
where a mountain knot is formed by the intersection of a 
short but well-defined transverse axis, running east and 
west, and nearly parallel with the great transverse axis to 
the northward ; the road over which at Petrania, between 
Cosenza and Nicastro, reaches an elevation of nearly 
3,400 feet. 

This transverse chain is, in fact, the dam, that absorbs 
the earthquake movements of Calabria Ultra, and prevents 
their full spread northwards, and trice versa, just as the 
great transverse chain of Monte Acuto, partially stops the 
propagation northward, of the shocks from the Principatas 
and Basilicata. At the intersection of the transverse 
axis of Monte Acuto, with the north and south one, there 
is a great mountain knot, comprised between Laviano and 
Oppido, east and west, and Venosa and Potenza, north and 
south. Within this space, which presents some of the 
grandest scenery of the Apennines, Muro and Bella occupy 
almost the central position. The mountainous country thus 
described, extends over about one half of the entire surface, 
of the kingdom of Naples. The remainder consists of vast 
plains, (relatively at least) of two distinct sorts— one, the 



THE GREAT PLAINS. 165 

rolling, rounded, hilly country, constituting the vast grazing 
downs, of Capitanata and Basilicata, on which countless 
sheep and goats are pastured in winter and spring; the 
other the rich com plains, level as the sea almost, of which 
the largest are in Otranto and Bari ; next to which come 
those of the Terra di Lavoro, the plain of Psestum, and of 
Calabria Ultra, from Bosamo to St. Euphemia (the scene of 
the great earthquake of 1784). All these great plains 
(piani) are on the seaboard, but almost every mountain 
yalley of any magnitude, consists of a piano, almost per- 
fectly level, from the sides of which, the mountains spring 
abruptly, as from a sea shore. The largest of these, is the 
Piano di Diano, in Principato Citeriore, the scene of some 
of the worst disasters of the earthquake of December, 1857, 
in early i^ring presenting, as do all these valley plains, 
characters of the richest and most enchanting country. 
The general aspect of the Yal di Diano may be gathered 
from the Photogs. Nos. 108 (and 109 Coll. Roy. Soc), being 
yiews of the town of Diano, from which the Yallone and 
Piano take their name ; the other of St. Arsenio, on the west 
side of \he same plain. The smaller valley bottoms, 
present the same characters upon a less scale — many are 
partially in forest. The mountain cincture of the piani, 
usually consists, of one or several sloping terraces of small 
elevation, having frequently the character, more or less 
perfect^ of ^^ parallel roads," tracing round the margins. 
Those in the J)iano of the Bay of St Euphemia, have been 
described by Meissonier, * Comptes Rendus for 1858,' 
and such terraces are observable around a large portion of 
the Yal di Diano. 
The piani are not always, or necessarily, strictly level 



166 GEOLOGY— THE LOWER ROCKS. 

plains, however; some slope, gently but contumonsly in 
one direction. 

Of the geology of the kingdom of Naples very little is 
accurately known. Within the parallels of 40° to 42°, the 
following are the leading figtcts so far as I have observed 
them, and learned from the sketch map of Italian geology 
of CoUigno. Probably the lowest and most ancient visible 
stratified rock is the Jurassic limestone, which constitutes the 

• 

central mass of the axial, and all the higher lateral chains. 

Lithologically, it is usually in heavy and well-marked 
beds, the line of strike being very commonly in the 
general direction of the chain, and the beds tilted to a high 
angle, so that a. very large proportion of the whole moun- 
tainous surface of the country, coiisists of highly inclined 
beds, running about north and south. There are, however, 
large exceptions to this : in the mountain knot, of Muro 
and Bella, amongst other places, for example, the beds, 
nearly vertical, often cross the lines of valley at right 
angles. Again, in the great range of La Scorza, or Monte 
Albano, — south of the Salaris, and between the Val di 
Diano and the Plain of Paestum — the beds support a lajge 
elevated and nearly level table land, with an east and west 
strike, and inclined at various angles dipping to the south, 
and are piled up fully 3,000 feet above the valley of the 
Rio Negro. They seem to dip inwards, towards the centre 
of the table on top, so as to rampart it all round : it is 
the largest surface of mountain table land in'the kingdom. 

Everywhere this lower limestone presents traces, of im- 
mense disturbance and dislocation, and of enormous denu- 
dation. 

Its colour is most commonly yellowish ash gray, and 



NUMMULITIC AND HIPPURITE LIMESTONE. 167 

when most compact, it has quite a liassic aspect in hand 
specimens ; it varies much in colour, however ; red, purple, 
variegated, and nearly white, are to be found. In many 
places it presents metamorphic characters, and becomes 
for limited areas, flinty and hard. 

A great band of this limestone, extends from around the 
Terra di Lavoro, southwards to the Gulf of Taranto, from 
thirty to forty miles wide on the west side ; it winds about, 
forming the summits of all the hills that rise out of the 
level bed of tufe, that surrounds Naples, and then stretches 
away northward in a still wider band to the eastward, and 
a narrower one to the westward, sides of the peninsula. A 
large region from Barletta to Gioia, on the Adriatic coast, 
also consists of it. Within the first-mentioned band, and 
resting upon this limestone, are scattered immense deposits 
of a coarse calcareous breccia, consisting of rounded masses 
of various sizes, (sometimes, as north of Potenza, very large, 
reaching eight or ten feet in diameter,) and cemented 
together, with similar but softer material, in ill-defined 
heavy beds, usually much less inclined, than those of the 
limestone beneath. Whether this rock belongs to the cre- 
taceous series, or to what other, I am unable to say : it 
occupies the bottom of many of the narrow valleys, and in 
one place on CoUegno's map, appears to be assigned to the 
pliocene tertiaries, but probably in error. 

Above the lower limestone, reposing upon it, laid against 
its highly-inclined beds, and often mixed with it, in per- 
plexing confasion — we find the nummulitic and hippurite 
limestones of the cretaceous formation, always charac- 
terized to the eye, even &r away, by the want of clear 
bedding, the more rounded outlines, of the lower moun- 



168 SUB-APENNINE MARLS— GYPSUM. 

tains composed of it, and by its brighter colour. It is 
usually nearly white, often suflSciently hard and dense to 
work well, as a beautiful building material, capable of a 
good polish ; but also passing insensibly, within a few 
miles, into a soft, sandy stuflf, of little coherence, like a com- 
pound of English chalk, and fine white Dorsetshire sand, but 
still forming rocky eminences several hundred feet in height. 

Upon this again appear to lie, chiefly in the bottoms and 
on the flanks of the valleys, beds of marls of various tints, 
of enormous thickness — 600 or 700 feet in some places. 
These I presume to be the sub-Apennine marls of 
Collegno. 

In the lowermost portion of these marls, beds of yellow 
and brown sandstone occur, here and there of great thick- 
ness; in some places, they are traversed by beds of 
indurated, highly ferruginous and magnetic, dark gray 
calcareous rock, — by beds of gypsum, — and in very many 
places, give evidence of metamorphism. The beds, usually 
soft and sectile, and acted on with immense rapidity by 
river erosion, being converted into masses of striped 
jasper, often of great beauty and extreme hardness. 

In the neighbourhood of Potenza, there are large deve- 
lopments of indurated argillaceous slaty beds, of dark 
blue gray colour, which Collegno appears to refer to these 
sub-Apennine marls, but which appeared to me widely 
different, in lithological character at least, fi:om those last 
referred to. 

Above these marls, reposes, the usually great depth of 
alluvial clays, which constitute the valley bottoms. 

The tops and flanks, of the upper and lower limestone 
mountains, are almost always nearly bare of soil ; it has 



SOILS— PALLS OP THE GREAT RIVBBS. 169 

been all swept oflF from them and levelled under water in 
the valley bottoms, to form these rich plains of agriculture. 
The soil is commonly a dense tenacious brown or red brown 
loam, often free from stone for large areas, and composed 
of the detritus of the calcareous and argillaceous rocks. 
That combining the sand of the cretaceous rocks, and the 
clay of the marl beds, is of high fertility. 

Where the fell is small, the rivers (as the Tanagro in 
the Val di Diano) run slowly, upon beds of these clays, and 
form for themselves a permanent bottom, paved by the 
angular fragments and boulders of limestone washed from 
the soil ; but when the fall is rapid, as in the Rio Agri — ^a 
view in the valley of which, is given in Photog. No. 110 
(Coll. Roy. Soc.), then erosion takes place upon a scale 
of great grandeur. The alluvial soil is cut through to the 
bottom; the marl beds follow it; and the river runs 
upon a bed of loose blocks of limestone, resting on the bare 
rock, at the bottom of a ravine or " nullah," with steep 
sloping banks, which are continually washing away and 
slipping in, and at a level often of 300 to 700 feet below the 
flat of the piano, or valley bottom, that spreads out above, 
for miles at either side. The rocks in the foreground of this 
photograph, are of the calcareous breccia described. The 
rivers themselves, fed by the heavy rains of the wet season, 
which fell with something of the regularity and violence of 
the tropical rainy seasons, by the wet of winter, and by 
the sudden melting off, of the vast masses of snow that fall 
on the higher ridges, (and at elevations exceeding 2,000 feet 
above the sea, lie accumulating during winter,) are of a 
torrential character, and almost all flow thick, and turbid 
with brown alluvial sediment, to the sea. 



170 DENUDATION— TUFAS OVER UMBBTONEF. 

North of the great transvecBe ridge about Atellai we 
begin to encounter the great tofst deposit, of the ancient 
volcanic region aronnd Monte Vulture, and extending 
northward to beyond Melfi, where it is evident that denu- 
dation, has levelled and spread out, over the limestone, pro- 
digious quantities of the tufas and decomposed lavas, at a 
period probably long anterior to the ejection, of the earliest 
of the tufas of the Yesuvian tract, and where torrent and 
rain erosion, present features of the largest, and most 
instructive character. 

Details, either of that, or of the Vesuvian volcanic 
tract, are beside our present purpose, however, except to 
remark, that in both, the limestone laps in under the super- 
ficial volcanic products to an immense distance ; indeed, in 
the Terra di Lavoro — as we travel, for example, fix)m Naples 
to Caserta and Capua — it is obvious that the level plain of 
tufa over which we pass, out of which the limestone moun- 
tains rise sheer and abrupt on all sides, has been run in and 
levelled between them, and has traced out by its sur&ce, 
the contour, of every sinuosity of their narrow winding 
valleys, when all were under water, and that the limestone 
of the hills, in reality underlies almost the whole of the 
great tu& bed. Earthquake vibrations, therefore, pene- 
trate both these volcanic regions, through the intervention 
of the harder and more elastic limestone beneath, the 
tufas being thus shaken like plastic clay in a saucer, just 
as the great alluvial beds in the more southern valleys, are 
shaken by the vibrations, primarily propagated through the 
limestone surrounding them. Of the two, probably the 
tufa is the worse material, for the easy propagation of 
earth wave. 



CONNECTION OF VALLEYS— RIVER COURSES. 171 

The connection between one valley and another, at a not 
greatly diflferent level, is not unfrequently through a gorge 
or serrated cleft, fractured through the rock, in the bottom 
of which a torrent roars, while the road or mule tract is 
over the shoulder above ; such are Campostrina, between 
the valleys of the Calore and Tanagro — and that of the 
Gioija, at Muro. In general, however, the valley bottoms 
are at diflferent levels, and are reached by passing over 
low shoulders between them, the streams finding vent in 
sinuous, but not very deep ravines. 

The lower mountain ranges, of the cretaceous limestone 
are not very steep, though the slopes can nowhere, except 
in the rolling plain country, be called gentle. The higher 
ridges, are always steep, and frequently characterized by 
a shaggy bristling grandeur, of crest and outUne, greater 
than one is prepared to find in mountains, of a formation 
so recent. 

The fall of the rivers generally, throughout the kingdom 
is rapid, the mean breadth of the land, not giving an average 
length of bed, of much above a hundred miles, in which the 
average fsJl is probably above 3,000 feet; and even the 
great rivers, have their volume so augmented in winter, that 
on reaching the seaboard plains, their velocity is still very 
great, on debouching into the sea. Thus, the Salaris, after 
having traversed the plain of Paestum, retains a mid- 
sur&ce, winter velocity, of about eight feet per second. 

The towns in the earthquake region to which this Report 
refers, are nearly all built, as stated, upon rocky eminences, 
within the mountainous region; in some cases, however, 
within it, they are (or were) built upon the alluvial day 
deposit, on the level of their respective Piani. 



172 POSITION OF TOWNS— GEOLOGIC MBMOIKS. 

In the Capitanatas, Basilicatas, and Bari, there are 
many towns — some of them large and important, that stand 
upon the plain, or on elevated knolls upon it — none, with 
the exception of some on the coasts, such as Amalfi, are 
found nestling into valley bottoms of small size, as in 
colder climates, and such towns are usually of extreme 
antiquity. 

In the Appendix (No. 1) to this part, a translation is 
given, of that portion of the report of Professors Palmieri 
and Scacchi, on the Melfi earthquake of 1851, which com- 
prises their general account of the geology of Southern Italy. 
Although still leaving much to be desired, it is the best 
sketch I have been able to meet with. 

A few monographic memoirs on Neapolitan geology 
exist, such as Elie de Beaumont's, and others, on the Lignite 
formation of Calabria (* Comptes Rendus,' 1858). 

Collegno's 'Elemente di Gkologia Practica e Theore- 
tica,' Torino, 1847, contains a good deal of information as 
to the geology of Central and Northern Italy, with sections 
of the Northern Apennines; and so also does Pilla's 
'Saggio Comparative die Terreni d'ltalia,' and his * Trat- 
tato di Geologia' (Pisa, 1847-51) ; but for Southern Italy 
I have met with no corresponding information. 



APPENDIX TO PART L 



No. (I.) 

Trcmdatian of the general account of the Qeohgy of Sovthem.Italyy 
forming Chapter I. Part I, of Profs. Pcdmieri and ScacchCs 
account of the Earthquake of l^th August, 1851. 

* Delia Begiani Vulcaauca del Monte VvJturiy e del 7}remuoto ivi 
Awenuto nel de 14 Agosto, 1851, relazione fatta per incarico 
detta Beak Accademia deUe Sdeme, da Liugi Palmieri ed 
Archangdo ScacchL* Napoli Gaetano Nobili, 1852. 



OF THE NEPTXJNIAN EOCKS THROUGH WHICH THE 
VOLCANOES OF VULTURE FORCED THEIR WAY. 

The ancient fires of the region of Vulture opened a road for 
themselves through the neptunian rocks, which are not materially 
different from those which surround the other volcanic districts of 
Campania. The examination which we have made of the neptu- 
nian rocks of our kingdom from Balzorano, in the southern limits 
of Abruzzi, to Tarentum in Puglia, and Pizzo in Calabria, has 
proved to us that the same rocks occur everywhere in the same 
order, wd with nearly the same topographical conditions. 
Geologists who have visited these countries have met with no 



1 74 DIVISION OP FORMATIONS. 

slight difficulty in establishing a diyision in these sedimentary 
rocks, according to the order in which they have been deposited ; 
and the difficulty has not been diminished by comparing them 
with rocks of determined epoch, which might be contemporary 
with ours. For us, who have not had the advantage of seeing in 
their natural position any of the various sedimentary formations 
(except those of the kingdom of Naples), the difficulty has been still 
greater, nor can we flatter ourselves that we have surmounted it 
Meanwhile, without entering into discussions which would be 
foreign to the principal aim of our work, but keeping to what 
appears to us to agree with our observations, we prefer to divide 
our neptunian rocks into three series, that is, three distinct forma- 
tions. In the first series we shaU include all those calcareous rocks 
which are particularly characterized by Nummulites^ NerinesB, and 
those organic forms of which we have no example in the fieiuna of 
the present epoch, and which paleontologists, uncertain of their real 
nature, have denominated rudimentary. {RudktL) The greater 
part of our Apennine mountains being formed of this calcareous rock, 
we shall retain for it exclusively the name of {Calcarea Apennina) 
Apennine limestone. The rocks of the second series, verj 
varied in their mineralogical composition, agree in being distinctly 
stratified, in being almost entirely destitute of animal fossils, and 
in sometimes containing a great quantity of vegetable fossils of the 
Fucoid order. Although it is not easy to find Fuciform impres- 
sions everywhere in rocks of this formation, nothing better indi- 
cates their character than the presence of these plants ; for the 
absence or extreme rarity of animal fossils is a negative charac- 
teristic which in exceptional cases may be afiirmed of every species 
of rock. The last series comprehends marls, limestone, and sand- 
stone, abounding in marine fossils, the greater nimiber of which 
belong to species which now exist in our seas. To these rocks 
we shall confine the name sub- Apennine, although others else- 
where have designated some of the rocks of the preceding series 
with this denomination. They undoubtedly belong to the super- 
cretaceous period; and if the igneous phenomena of Epomeo in 
the Phlegrean region, as we have shown elsewhere,* have pre- 

* Scaochi. * Geological Memoir of Campania.* Naples: 1849. Pp. 19, 20. 



APENNINE LIMESTONE. 175 

ceded some nearly supercFetaceous deposits; yet in the Vulture 
district, where the order of position between the neptunian and 
volcanic rocks is in several places very easily seen, I have never 
found the igneous rocks, lying beneath any of the various rocks 
of the third series ; so that we may maintain that the emergence 
from the sea of the sub-Apennine deposits, took place premudy to 
the first fires of the Vulture. There are also in this same volcanic 
region frequent and extensive fresh-water formations; but, contrary 
to what ha8 been observed of the marine depoeite, they Ue invari- 
ably above the rocks of igneous origin, and closely resemble the 
sedimentary deposits which are in process of deposition in our own 
days, under very restricted conditions, in like places abounding in 
water. Punning a chronological order, we shaU briefly speak of 
these when we have concluded our remarks on the volcanoes of 
the Vulture district. 

First Series. — Apennine Limestone. 

The rocks of which the oldest formations of aqueous origin in the 
kingdom of Naples are composed, are almost exclusively calcareous, 
and include many varieties, which seldom constitute an essential 
difference. The most frequent of these varieties is the compact, 
with oonchoidal fracture, of a white, or clear smoke-gray colour. 
Another variety, somewhat less abundant, has a granular texture 
more or less distinct, in which oftener than in the preceding, small 
cavities lined with crystals of the same substance are found Pass- 
ing over several varieties of minor importance, we shaU enumerate 
four others. The first has a brecciated structure, enlivened by gay 
colours, and is capable of receiving a beautiful polish. Of this we 
have magnificent specimens in the marbles of Vitulano, and Mon- 
dragone> in Terra di Lavoro. The second is of a beautifril white 
colour, and pulverizes easily at a touch. It may be seen between 
Piedimonte di Alife and S. Potito at the foot of Matese in the 
district of Melfi, after the 77th milestone on the road from Valva, 
and in many other places. The third variety, not very different 
from the preceding in appearance, is that which geologists denomi- 
nate chalk, and which, so far as we know, is only found at Monte 



176 VARIETIES CONTINUED— SILEX. 

Gargano*. The fourth is bitaminonsy and is met with in many 
places, particularly in those which abound with Ichthyolitic fossUflu 
Quartz or Firestone (Pir&maeo) is so frequently found in limestone 
of this series^ that it may be considered characteristic of it Some- 
times it appears in veins at the junction of the thicker calcareous 
strata^ but more frequently it is imbedded in them^ ftiwnTniTig various 
%ures^ among which the spherical is remarkably perfect Astonish- 
ment at the perfection of the globular figure of these Bognom di 
Piromaco t has occasionally given rise to the foolish supposition that 
they are areolitea The manner in which this variety of quartz is 
found in the limestone clearly proves it to have had the same 
origin as the rock which contains it ; and this is corroborated by 
the frequent cases in which it partly or entirely takes the place of 
the carbonate of lime, of which the fossils endosed in the same 
rock were originally formed. In such cases it is worthy of note, 
that the other variety of crystallized quartz is occasionally united to 
the Piromaco. With our present chemical knowledge, we can 
easily understand that silex, as well as carbonate of lime, may have 
been held in solution in the water by which they were deposited. 
But we cannot, with the same facility, account for the silex being 
precipitated in the state of Piromaco, or as crystallized quartz, 
whilst we know that silex is naturally deposited by some mineral 
springs, or artificially by solution in concentrated waters, with the 
qualities proper to ChieaeritCf or hydrate of silex. Perhaps arguing 
bom the frequency with which fossils are found converted into 
Piromaco, we may attribute its presence to organic substances, 
as Becquerel observed that organic substances in a state of 
putrefaction, deposit crystals of pyrites in a solution of sulphate 
of iron. 

Carbonate of magnesia, in widely-varying proportions, is always 
united to carbonated Apennine limestone. The large quantity 
which is occasionally foimd, we think, must be attributed to the 
facility with which, in some places more than others, this rock 
imdergoes great changes, caused by the continual influence of 

* Limestone passing into clialk is found abundantly in many other places, 
especially in the lateral valleys to the westward of Padula.— R. M. 
t Kidney-formed masses. 



DOLOMITE. 177 

the weather (meteori). One of the most surprising examples of 
this kind of decay may be observed in the upper part of the 
valley of Tramonti, in the province of Salerno, where the pheno- 
menon extends over a large tract of ground. In some places, as in 
the vicinity of Amalfi, the magnesian limestone presents the charac- 
teristics of Dolomite, having a granular texture, and dissolving 
slowly in acids. However, we cannot subscribe to the opinion of 
those who attribute the presence of magnesia to the action of in- 
ternal plutonic masses, which have given to the sedimentary lime- 
stone rocks the characteristics of Dolomite. There is no ground 
for refutation of the opinion, that true Dolomite is of neptunian 
origin, and therefore its presence is insufficient to prove that the 
change has been occasioned by plutonic rocks. And the reasons 
which prevent oiu* applying the theory of dolomization to our 
Apennine moimtains are — 1st The absence of plutonic rocks in 
their vicinity, which might occasion the phenomenon. 2nd. The rare 
occiuTence of true Dolomite, and the fact that it is confusedly mixed 
with magnesian limestone, which does not possess the distinctive 
characteristics of Dolomite. And, lastly, the organic forms of well- 
preserved fossils in those rocks which most manifest dolomitic qua- 
lities. The last is one of the best arguments against the maintenance 
of the Dolomite theory in reference to our magnesian limestones, but 
of it we do not find many examples. We might conclude that the pre- 
sence in great quantity of carbonate of magnesia is adverse to the 
propagation of marine animals, or that it has contributed to the 
destruction of the shells of the ancient fauna. In the Dolomite of 
Amalfi, where we foimd several well-preserved casts of Terrebratulse 
and Ammonites, this opinion is still further strengthened ; for in all 
the examples which we examined their shells were entirely destroyed. 
The preceding considerations, however adverse to the phenomenon of 
dolomization in the rocks of our Apennines, do not exclude the 
internal plutonic forces, by which they were disturbed from their 
primitive position, and raised to their present height ; nor the pheno- 
menon of metamorphosis, which is clearly manifested in some parti- 
cular districts, where limestone is found at a short- distance from 
crystalline rocks of igneous origin. In the district of Castrovillari, 
perhaps more than anywhere else, frequent examples of metamor- 
VOL. T. N 



178 NUMMULITES. 

phosed Apennine limestone are met with. It acquires a granular crys- 
talline texture, not imlike statuary marble, and contains passing 
through it some thin veins of quartz, with chlorite, many crystals of 
pyrites, and sometimes cinnabar, and the traces of fossils are very 
nearly obliterated. There are yet more evident proofe of metamor- 
])li03is in the rocks of the succeeding series, which are changed into 
Quartzite, Stannite, Talc, and schistose argil, all of which are found 
in the limestone of the region. Tlie Apennine limestone has gene- 
rally been reported poor in organic remains, which might furnish 
paleontologists with determined characteristics. Oiu* researches lead 
us to a contrary opinion ; but as we cannot, without deviating from 
the design of om* work, enter into an examination of the diflferent 
species of fossils which we have found, it must suffice to say, ih^t 
the number of species, and the quantity of each kind, are such as 
to give us a correct idea of the abimdant faima of the sea, in whose 
depths our highest mountains were formed. Any who wish for a 
convincing proof of this assertion may find it in the rich collections 
which, within the last few years, have been deposited in the Mine- 
ralogical Museum of the Koyal University of Naples. The most 
frequent and abimdant organic forms which we have found belong 
to the RudistL and of these we may say, that there is no place in 
which we cannot discern their trace ; and in some spots, whether 
owing to the nature of the rock in which the fossils are preserved, 
or from the habits of those animals to live in myriads in a small 
space, the quantity is so enormous, that the entire rock apjxjars to 
be composed of them. Monte Gargano, Monte Lesiile, in Matese, 
the brown limestone of H Ponto Consolazione, near Lauria, in 
Basilicata, present striking: examples. Although they are usually 
so completely petrified, and identified with the rock itself, so as to 
render the determination of the species diflicult, yet by attentive 
examination we can distinguish a difference between those found in 
places not very distant from each other. Tlie large sj)ecie8 of 
Nummulites next claim our attention ; and while, like the JRudisti, 
or even more strikingly, they are found united together in myriads 
in one place, they are not, like them, distributed over a large 
district. In many extensive districts they are in vain sought for. 
Besides, in Monte Gargano. and the neighbourmg islands of Tremiti, 



OTHER FOSSILS. 179 

reno^^Tied for fossils of tliis kind, no contemptible deposits are 
found in the vicinity of Lama, in Abruzzi, near Casalbone, and not 
far fix)m Ariano, in the province of Avellino, and in the territory of 
Benevento (Olivella di Pacca), where they are disseminated tlu-ough 
limestone and Piromaco. The nerinsBa, another kind of mollusc, 
which deserves our attention, usually accompanies the RudiMi, and 
is foimd in many places ; several species, diflfering in size and form, 
being recognizable. Besides these tlu-ee groups of fossils — to 
mention but a few examples of a long series, containing many 
species, some of which probably ought to constitute new genera — 
we must record, in the province of Terra di Lavoro, the spiral shells 
of the LumacheUe of Monte Casino and Vitulano, the Diceratiti of 
Monte Licinio, near Cerreto, and some shells, allied to the Natichey 
of Monte Lesule, in Matese. In Monte Gargano there are also some 
remarkable impressions of plants, probably of the family of the 
conifers, two gigantic specimens of Bulle, a Pirula, and Ammonites 
Eothemagensis ; and in this same moimtain, as well as in the vicinity 
of Amalfi, and near Castelgrande, in the district of Melfi, different 
species of zoophytes are not scarce. As to our ichthyolites, of which 
but few species were known before the recent works of Costa (Costa, 
* Paleontology of the Kingdom of Naples, 1850'), we are now 
acquainted with a great many in the mountains of Pietraroia, 
Giffuni, and Castellamare ; and by the discoveries also of Pro- 
fessor Costa, of which as yet only a brief accoimt has been 
published (Costa, * Hints relative to the Discoveries of the Paleon- 
tology of tlus Kingdom made in the year 1851 '), we have made 
out at Ketraroia, in the icthyolitic limestone, some species of rep- 
tiles. From the brief account we have given of the fossils found in 
the Apennine limestone, it is easy enough to iofer that all, or at 
least the greater part of them, belong to the great Chalk formation. 
But fix)m such observations as have hitherto been made, although 
we cannot say that they are suflBciently numerous, it is not equally 
easy to establish any di\'ision among them ; nor can we decide with 
any certainty whether some of them may not belong to still more 
ancient formations. Yet, not knowing of any instance in which Rvdigti 
have been found in those rocks which contain the fossil fish at Gifiuni, 
Pietraroia, and Castellamare, we are inclined to think that they 

N 2 



180 THE MURGE. 

ought to be placed in the Jurassic group. Meanwhile we consider 
it better to refrain from putting forward ill-grounded opinions, and 
to defer the solution of this question until a future day shall bring 
more decided facts to light ; for at present, so far as our knowledge 
extends, ichthyoUtic limestone has not undoubtedly been found either 
above or below that which contains Rudistiy nor have any of our 
species of fossil fish been recognized in rocks of a well -determined 
epoch, although some species have been found in the chalk for- 
mation of Monte Gargano. The topographical character of moun- 
tains formed of Apennine limestone enables us to distinguish them 
at a great distance : their long narrow summits, the lesser ramifica- 
tions branching off from their sides, and dipping down till they 
end in an acute ridge, their slope not unfrequently broken by 
majestic steps, against which the inferior rocks lean, as if c^:ainst a 
firm vertical wall, the strata of which they are composed appearing 
gradually to tilt up, as if they would touch with their ends the 
high acclivities, and even the most elevated ridges, form so charac- 
teristic an aspect, that they are easily distinguished fix)m neigh- 
bouring mountains and hills of a different nature. Admitting a few 
unimportant exceptions to this general order of topographical con- 
figuration, the fact of greatest significance to which it is necessary 
to direct attention is, that the same Apennine limestone which is 
visibly displayed to a great extent in the provinces of Capitanata, Bari, 
and Lecee, there assumes a completely different aspect. We find 
loAV hills, commonly called Murge, in the province of Bari, extending 
in various directions, and sloping do^^^l to a vast plain, which with 
the mountainous region forms a winding line from north-west to 
soutli-east, almost parallel with the coast of the Adriatic, that extends 
from the Gulf of Manfredonia to Brindisi. To the characteristic 
outline essential to tlie Murge we must add the no less important 
cliaracter apparent in the arrangement of the strata, which, besides 
being more distinct tlian is usually observed in mountains, is gene- 
rally horizontal, or somewhat inclined to tlie horizon. These dif- 
ferences between the i)erpendicular strata of the mountainous 
regions, and the horizontal strata of the low hills, sufficiently prove 
the elevation, or at least tlie great displacement, to wliich the 
former were subjected ; wliile the latter have preserved the same 



MACIGNO. 181 

position in which they were originally deposited, relatively at least 
to the horizon, if not to their distance fix>m the centre of the earth. 
It might be thought that the limestone of the Murge, the stratifi- 
cation of which is so diflferent fix)m that of the mountains, was 
deposited at a later period ; and this would appear to verify the 
opinions of tliose geologists who, unacquainted with the fossils 
it contains, considered it to belong to the super-cretaceous period. 
But the frequent occurrence of Hippurites in it contradicts this 
opinion, and as we find it agrees in paleontological characteristics 
with the limestone of the Apennines, we are compelled to hold 
them contemporary. Nor can we find any other reason for the 
difference of stratification except that now mentioned, viz., that 
the first was not subjected to the internal plutonic forces of our 
planet 

• 

Second Series, — EocKS with Fucoids, or the Macigno 

Formation. 

Generally speaking, their topographical aspect suflSciently distin- 
guishes the rocks of this series from those of the preceding ; and, 
although they are often foimd in the elevated regioiis of the Apen- 
nines, yet they never form great chains of mountains. Their usual 
appearance is that of small mountains or hills, with rounded and 
depressed summits, and in a few cases, where the strata are unu- 
sually thick, and greatly elevated, they assume the appearance of 
limestone mountains. The old summit on which the city of Monte- 
"verde is built, and which rises much above the lesser prominences 
which surround it, furnishes us with a most striking example of this 
effect ; and even here, though the developed form of the mountain 
is an exception to the general rule, yet its height does not equal 
that of the ordinary limestone mountain masses. The different 
species of rocks which compose this formation are remarkable for 
the manner in which they are stratified, frequently alternating with 
each other, and presenting the most beautiful appearance of regu- 
larly disposed strata, the one kind surprisingly distinct from the 
other. The ordinary thickness of the strata varies from a decimeter 
to half a meter. Instances of great thickness are less frequent, 



182 ITS STRATIFICATION. 

and occasionally tlie layers are very thin. The most important 
point observable in these rocks is their strange position, so highly 
inclined to the horizon. The distinct development of the strata 
enables us to determine their degree of inclination and direction 
with great acciu*ac*y ; yet as to their direction we have not been 
able to ascertain towards what point they are generally elevated, 
the direction of their inclination being found very various even in 
places separated by short distances. The angle of inclination also 
is very uncertain, varying often between 25 and 50 degrees ; nor 
are instances rare in which it attains to 70 or more degrees, and in 
some places the strata might be called vertical. In no other of our 
sedimentary rocks have we better evidence of the great displace- 
ment which must have occurred, than in that wliich the great 
inclination of these strata presents, as it is imix)ssible to conceive 
how they could have been deposited as they now appear. Yet it is 
in rocks of this series that we find the greatest diflSculty in assigning 
the true cause of this fact. First of all, finding several strata of 
clay which crumble easily, on accoimt of the softness which they 
acquire from the absorption of water, and the limestone and sand- 
stone strata having, on accoimt of their thinness, but little resist 
ance, we are justly inclined to think tliat the elevation of the strata 
is the effect of the rents occasioned by the contiimal miTiing of 
subterranean water. Admitting the possibility of this reason, and 
maintaining that it may have in some measure effected the change 
of tlie primitive situation of the stratified rocks of tliis series, it is 
not probable that it alone, could have produced such great effects, 
and often in an uniform manner over a great space, as observation 
has made knoA\Ti to us. In many places it is entirely impossible 
that any other cause than that of plutonic forces, having their 
seat at a great depth beneath the terrestrial surface, coidd have, so 
strangely and throughout entire regions, elevated the enormous 
stratified masses, and thus disciovered their internal structure ; but 
for wliich we should never have bt^en conveniently enabled to 
examine them, and j)erhaps might still have remained in igno- 
rance. And noAV, for a clear explanation how catastroi^hes of a like 
nature appear to us to have happened, it is necessary to declare, 
that if, by relating facts as they first appear to sense, we have 



ELEVATION OF THE LIMESTONES 183 

attributed the actual position of strata incKned to tlie horizon to 
elevation, this does not exclude the idea of undermining operations. 
And since, whether they have been elevated or whether they have 
been undermined, we shoidd always find their prunitive horizontal 
position deranged in the same manner, it is not easy to decide wliich 
of the two conditions has rendered the region mountainous, or, if 
both were in operation, which of the two has had the greater 
influence. For if we consider the general pliysical property of 
matter to diminish in volume by the decrease of its temperature, 
the theory at pre^nt held by all, of the primitive state of igneous 
fusion of our planet, leads us to the necessary consequence, that in 
cooling it must have diminished in size, and the forces which have 
acted on its consolidated crust must induce it to approach the 
centre. In the district occupied by the volcanoes of the Vulture, 
other particular considerations present themselves to the mind of 
the geologist who contemplates the strata of the neptimian rocks, 
here, perhaps, more elevated than elsewhere. As we sliall pre- 
sently state, these volcjanoes are surrounded on every side by hills, 
formed of rocks of the second and third series, which must have 
felt the effects of the disturbing volcanic eruptions, and there- 
fore it is easy to attribute their elevation to the same eruptions. 
In the east side of the base of Mount Vulture, along the line occupied 
by the cities of Melfi, HapoUa, Barili, and Kionero, in many places 
it is eaay to observe the strata of limestone and red marl beneath 
the lavas and volcanic conglomerates, with the ordinary character 
of elevation proper to this formation. Half way on the road 
between Rionero and Barili, on the left-hand side going from 
Bionero, in the place denominated the Valle del Salice, a long 
series of the outcrops of stratified rocks, wlucli form tlie bed of a 
brook which flows over them, is seen. The average of their in- 
clination, though variable, is about 70 degrees, and they are 
elevated fix)m the side turned towards the east and south-east. It 
is enough to say that they are inclined in a contrary direction to 
tlie slope of the Vulture, to prove it impossible to attribute their 
elevation to an internal force, whose centre of action should 
coincide with the central part of the volcano. The same thing 
may be observed in many places on the same road, so that this 



184 PRIOR TO VOLCANIC ACTION. 

arrangement of strata is invariable for upwards of a mile. And to 
this fact sm^ly Fonseca allades, when he says that between Rionero 
and Barili the limestone strata are inclined almost at right angles 
to the declivity of the mountain. (Fonseca, * Geognostic Observa- 
tions on the Vulture.') Along a brook which runs near Barili, from 
the north-west side, the same strata of limestone and marl on the 
right bank are elevated towards the west 44 degrees, and on the 
left bank, towards the north, 31 degrees ; and, one being almost 
opposite the other, their displacement cannot be referred to the 
action of the Vulture. In a valley situated to the north of Bapolla, 
the waters which run through it pass over limestone strata ; and in 
one place where these are very apparent we have found them 
elevated 55 degrees towards the north-east, not to mention some 
which are even nearer to the vertical position. Lastly, omitting other 
facts of a similar nature which are less conspicuous, along the little 
river which runs round the hill of Melfi in the north-west side, 
some strata of grey argil are seen, which have the same inclination 
as the hill ; and in the west side, not very distant from the bridge, 
commonly called Gaetaniello, there are some strata of red marl, 
containing fucoids, inclined 70 degrees towards the north-east 
Their elevation cannot l)e attributed to the principal volcanoes of 
the Vulture ; nor does it agree with the centre of action of the 
volcano of Melfi, as then they would have been inclined to the 
east. From these facts it is natural to conclude that the displace- 
ments observable in the neptunian rocks of the volcanic region of 
Vulture were not occasioned by the same forces which gave rise to 
the volcanoes, but rather that they occurred previously to their 
eruptions. This opinion is strengthened by the fact, that they 
present the same appearances as have been observed in other 
places, where the distance from the Vulture and the particular 
manner of dislocation prove that tlie eruptive volcanic force could 
not have occasioned such displacements. We shall select^ from 
many instances which we might quote, that of the lofty eminence 
whicli we recently mentioned, on which the city of Monteverde 
is built. It lies to the north-west, distant in a direct line little 
more than four miles from the lakes of Monticchio. It is chiefly 
composed of large strata of Macigno, some of which are upwards of 



SMALL LIMITS OF VOLCANIC ELEVATIONS. 185 

four metres in diameter ; and in the southern summit, called Sierra 
della Croce, the strata being laid bare by several hollows, show an 
inclination of 47 degrees ; and fi-om this side rises another opposite 
summit, having the same inclination, from which we may con- 
jecture that the Sierra della Croce has been separated from it. 
Therefore, even supposing we admit that the internal impulse 
accompanying the fires of the Vulture, having its centre in the 
neighbouring lakes of Monticchio, may have extended to a great 
distance, it is impossible that the actual arrangement of stratifi- 
cation of the Macigno of Monteverde could have been occasioned 
by it : an order not essentially difierent from that of the stratified 
rocks which are displayed from Melfi to Rionero. 

In the district of the Vulture, much better than in any other 
volcanic region of our kingdom, we can observe the manner in 
which the volcam'c rocks interstratify with the neptunian; and, 
comparing them with the observations here collected, we cannot 
reconcile them with the idea that volcanic forces could have had 
80 extensive a field of action near the terrestrial surface. On the 
contrary, we are led to the opposite opinion, namely, that the 
space is very limited in which volcanic explosions can occasion 
elevations or other perturbations of ground, and that the first con- 
vulsions are almost always concocted under the materials which 
are subsequently ejected. As we must return to this argument in 
another part of our work, what we have already said is sufiScient to 
testify, that in our opinion the volcanoes of the Vulture have had 
no part in the elevation of the rocks of the second series, in which 
they have appeared. 

The relation of arrangement between these rocks and the 
Apennine limestone presents another field of inquiry, in which 
it is not easy to see clearly. Is it beyond a doubt that the former 
belong to a period subsequent to the latter ? Are the elevations 
of the first cotemporary with the elevation of the second ? Have 
they been once or oftener convulsed ? What difierence of condi- 
tions results from the diflference of composition between the rocks 
of the first and second series ? These are the principal questions 
^hich the geologist is compelled to discuss. We shall speak of the 
last when we have given the necessary mineralogical description of 



186 ORDER OF SUCCESSION IN APENNINES. 

the nnmerons fucoidal rocks. As to the first question, we must 
admit that, throughout Campania and the greater part of the 
Principatas, we cannot, generally speaking, perceive with sufficient 
clearness the super-position of one system of rocks above the other. 
Not so in Lucania: there the super-position of the fucoid strata 
above the Apennine limestone is very evident^ and their condi- 
tions are notably different. These observations have induced us to 
maintain, not only that the former were laid down at a subsequent 
period to the latter, but also, what is still more important^ that 
they belong to two distinct formations. Perhaps the most suitable 
place for examining these conditions is the Valva Boad, along 
which, from Oliveto to within a few miles of Atella, we never lose 
sight of the line of contact between the hills of the second series 
and the mountains of the first The latter appear to come out from 
under the hills which lie roimd their bases ; and in some places, as 
at Fontana della Kose, between Laviano and Muro, the order of 
the strata which form the hills is clearly seen to rest upon the 
Apennine limestone. At the same time we can observe the dif- 
ference of direction and inclination of the strata belonging to the 
two systems : a discordance which is also manifested in the different 
topographical aspect of which we have already spoken, and which 
cannot exclusively depend on difference in mineralogical compo- 
sition of the rocks. As the strata of clays, sandstones, and lime- 
stones with fucoids, in the northern jjrovinces, do not possess any 
notable difference of composition from those in the southern, nor 
are the paleontological characteristics at all different, arguing from 
analogy, we consider them all to belong to the same formation, 
and are confirmed in this opinion by never having met with any 
fact which could clearly contradict it. From this diiierence between 
the Apennine limestone and the rocks of the second series we are 
led to infer, as a necessary consequence, that the former must have 
been displaced before the latter were deposited ; and again, these 
latter rocks being so much inclined is the proof of a second period 
of elevation. The manner in which the rocks of both series inter- 
stratify with each other appears to us sufficiently to declare that 
the more ancient formations cannot of necessity have been exempt 
from the disturbing force which displaced the more recent. Of 



THE FUCOID ROCKS. 187 

these general cjonjectures relative to the convulsions to which 
our sedimentary rocks have been subjected we find satisfactory 
proofs in the southern regions; whilst, on the contrary, in the 
northern, as we have already observed, the relation of arrangement 
between the rocks of both systems is not manifested with sufficient 
clearness, nor can we support the theory that the same phenomena 
have everywhere occurred. Having akeady observed that the 
Apennine limestone may be divided into two distinct regions, the 
one mountainous, the other almost level, called Murge, a fact of no 
sh'ght importance appeals to our consideration, relative to the dis- 
tribution of rocks of the second series in connection with this 
division, viz., that they only occur in the mountainous region. It 
was not without surprise that we traversed the province of Bari, 
and the neighbouring districts of the provinces of Lecce and Capi- 
tanata, seeking diligently, without success, for rocks of the second 
series, of which we never found a trace. We must confess that 
we C€umot clearly account for this circumstance. Where the moim- 
tains formed of Apennine limestone rise, there must certainly 
have been during the epoch in which the rocks of the second series 
were deposited, a topographical condition completely diflferent 
from the level plains. Ought this topographical difierence to be 
considered suflScient to prescribe the limits within which such rocks 
can be formed ? Now, as we shall presently show, among the com- 
ponents of these rocks, there are some which have very probably 
been transported from the granite mountains of Calabria, and in 
general consist of materials which may have come from distant 
places. Ought we to regard the direction in which their elements 
were transported as the cause of their being found in certain regions, 
and being wanting in others ? The mineralogical composition of 
the fucoidal rocks is extremely varied. We may divide them into 
five different species, viz., limestone, marl, sandstone, Umonite, and 
gypsum ; and each of these admits of being subdivided into many 
varieties, of which we shall only record the principal. The varie- 
ties of most frequent occurrence in the limestone are the marly, of 
various colours, sometimes with those beautifid appearances which 
take the designs of ruined buildings (calcarea ruiniforme). Another, 
less fi^uent, but not less characteristic, is a breccia, of verj' 



188 SANDSTONES— LIMONITE, 

minute fragmentB, with rose-coloured cement, sometimes intense, 
and again diffiised, bearing a great resemblance to red porphyry, 
consequently of lovely efiect in workmanship. The most beautifiil 
specimens of the calcarea ruiniforme are to be found in the neigh- 
bourhood of Gesualdo and Frigento, in the province of Avellino, 
and the second variety is more common in the district of Melfi 
than anywhere else. If the limestone of this series contains almost 
invariably some clay, the clays, on the other hand, are always 
mixed with some proportion of carbonate of lime, which gives them a 
marly character. They are sometimes compact (amorphous), but 
more frequently divided into thin laminae, without losing the pro- 
perty of forming with water a ductile paste. They are usually of a 
gray sky colour, and in Lucania are not unfrequently red. These 
rocks on one side pass by imperceptible degrees into limestone ; on 
the other beginning to contain minute particles of mica and small 
grains of sand, the latter gradually becoming more abundant, they 
change into sandstone. The sandstone itself, owing to the size of the 
grains of quartz, and their abundance or scarcity, and also to their 
varj^ing degree of tenacity, present innumerable differences, which 
are of no importance. They possess, for the most part, the cha- 
racteristics of true Macigno ; in some cases are good for sharpem'ng 
edged tools, and in others may be used with advantage for making 
bricks or crucibles capable of bearing a liigh temperature. The 
Limonito is seldom foimd pure, and its deposits are so scarce, that 
they can with difficulty be profitably used for the extraction of 
iron ; nevertheless, mixed with carbonate of lime, it is rather fre- 
quently found in each of the three preceding kinds of rocks, espe- 
cially in the limestones and marls. 

Ferruginous sandstones, occasionally mixed with deposits of 
Limonite, are not scarce in the district of the Vulture, and it is 
requisite to take care not to confase them Avith volcanic produo 
tions. When the limonite unites with marl, it occasions such 
strange fonns, that the naturalist no less than the uninitiated must 
regard them with astonishment. Besides what I have said 
relative to these U^gle stones, of which beautiful specimens are to 
be found in the district of Gerace, there are some remarkable 
varieties in tlie Fucino district near Pietraroia, which, from their 



BRECCIA— GRANITE BOULDERS. 189 

resemblance to pieces of petrified serpents, have been denominated 
serpentinu To these kinds of configuration we may add the 
spheroidical masses with laminated concentric structure, found in the 
vicinity of Alberona, in Capitanata, and the prismatic forms of the 
valley of Ansanto, outwardly composed of largo crusts of Limonite 
with Siderosay and filled interiorly with marl, and often with pieces 
of the same Limonite. In the sandstone, besides the minute grains 
and roimded pebbles (pezzetti rotolati) of quartz, of which it is 
essentially composed, pebbles of rock crystal are sometimes found 
in great abundance. For the most part they belong to the granite, 
quartzite, or porphyry, and vary greatly in size, increasing bom 
that of a filbert to about two decimeters in diameter. In occasional 
instances they are found of a surprising magnitude ; but these, as 
well as the smaller specimens, have a rounded surface. We may 
instance one, which was found above Monte Vergine, near Avellino, 
more than five decimeters in diameter ; and another, in the region 
called Fontana delle Rose, not far from Muro, whose greatest 
diameter was sixty-three centimeters. This last region, made known 
by the published works of Tenore and Gussone,* ought to be visited 
in preference to any other, by those who desire to examine the 
great roUed masses of granite which exist in our Apennines. On the 
road from Laviano to Atella, a Uttle past the seventy-first milestone, 
we met on the right-hand side, a path leading to a spacious valley, 
through which the waters of the Fontana delle Rose run. Along 
this rough path we often meet with large granite boulders, and in 
the valley following the course of the stream, several large isolated 
ones may be found. Of these last there can be no doubt, that, like 
tliose still imbedded in the sandstone, they too were inclosed in 
the rock, and when it was disintegrated they remained scattered as 
we see them through the vaUey. Many such rolled masses of 
granite, and of another kind of crystalline rock, are found along 
the River Olivento, commencing at the source under Ripa Can- 
dida, and extending to its junction with the torrent of Macera ; 
similar rocks are also found in other places surrounding the 
volcanic region of Vulture, or on the Vulture itselt We have seen 

• Tenore aiid Gussone. * Memoirs of Tours performed in the Years 1834-1838.' 
Naples : 1842. Pp. 75, 76. 



190 DILUVIUM FROM CALABRIA. 

some at the Bo8co di Gaudianella. When we have explained the 
relation of arrangements between the neptunian rocks of the 
third series and the volcanic, it will not be diflScult to understand 
how they came there. Lastly, among the districts in which 
numerous pebbles of rock crystal are observed, we must enumerate 
tlie vicinity of Pietraroia, remarkable for the great variety which is 
found there. Before we had observed the granites enclosed in the 
limestone of the Fontana delle Rose, we referred the blocks of the 
same kind found at Monte Vergine, and Pietraroia to the doubtful 
series of masses of similar rocks, sometimes of enormous size, 
called by geologists {erratici mam) erratic blocks.* We now 
class them in another group of rocks, and assert that their 
origin is not at all different from that of the minute grains of 
quartz, of wliich the Macigno of the fucoidal rocks is composed ; 
tlie grains as well as the spangles of mica which are frequently 
seen in clay, being minute particles of granite, or of some other 
crystalline rock. The greater number if not all the varieties of 
granite found in isolated blocks among the sedimentary rocks of 
the Apennines, resemble, in the most minute particulars of their 
sensible properties, the rocks of the same kind which we observed 
in their primitive arrangement in Calabria. If this is sufficient to 
assure to us that they owe their origin to the granitic mountains of 
Calabria, it will follow, that we must hold, that at least the greater 
part of the materials Avliieh form these rocks of the second series, 
was derived from these mountains ; for, it is indubitable that the 
elements of which they are fonned, must have been transported 
from regions many miles distant from the places where tliey are 
dejx)sited, and the mountains of Calabria from which they might 
have been taken, are the nearest. As to the inquir)^ into the 
origin of such impetuous and extensive torrents of water, possessing 
the force necessary for carrying down so large a quantity of waste 
material, tliis, we must admit, is a difficidt question, and perhaps 
tlie consideration of the maimer in which this transport was 
effected is still more ditlicult. 

Allowing every one to conceive tlie events of such remote epochs, 

* Scacclii. * Lessons in Geology.' Naples : 1842. P. 131. 



GYPSUM— ROCK SALT. 191 

according to his own measures of probability, and trusting to 
future researches to reveal to us the ancient history of the earth 
we tread, we shall confine ourselves to a few considerations relative 
to the manner in which the rocks we have undertaken to treat of 
were deposited. We find them mastly formed of thin strata with 
parallel surfaces, regularly deposited one over the other, and con- 
sisting alternately of strata of limestone, clay, and sandstone, thus 
proving the habitual tranquillity of the water beneath which they 
were deposited. On the other hand, the large rolled granite rocks 
testify that occasionally these same waters were violently agitated. 
Lastly, the great number of strata, the ends of which are visible in 
some places, assure us that the formation of the fiicoidal rocks must 
have occupied a long period. Gypsum is not so frequent or 
al)imdant in rocks of this series as in the other. Sometimes it is 
arranged in strata, or crystals of considerable size are scattered 
through the clay ; again, it forms large deposits which do not exhibit 
any signs of stratification : in this case its structure is eminently 
crystalline. An example of its extraordinary arrangement may be 
observed a little more than two miles to the west of Melfi, at a 
place called Masseria del Gesso, and a very large deposit occurs in 
the territory of Marcerinaro, in the province of Catanzaro, extend 
ing more than a mile. Observing the conditions of these deposits, 
and reflecting that gypsum is not so generally diffused as the other 
rocks of the same formation, we are of opinion that its origin must 
have depended on particular causes, probably of the same nature 
as those which in our days, on a smaller scale, are generating 
gypsum in the valley of Ansanto, in the i)rovince of Avellino. 
The largest crystals of gyi)sum formed in argil, are found close to 
the village of S. Potito, south-east of Piedimonte di Alife. It is 
not scarce in Terra di Lavoro, being foimd distinctly stratified near 
Mola di Gaeta, Casanova, Torrecuso, and in some other places. In 
the province of Cosenza, strata may be seen in the clay on the 
right bank of the torrent Pantusa, between Cerisano and Marano, 
and near the salt pits of Altamonte. In the last region gypsum 
forms a part of the immense dej)osits of Rock salt, of which (as it is 
foreign to the aim of this work to treat of them more particularly) 
we shall only say, that in our opinion they belong to the fucoidal 



192 FOSSILS OF THE MACIGNO. 

rocks, and their origin is analogous to that of gypsum. The fossil 
characteristics of the Macigno formation belong almost exclusively 
to the vegetable kingdom ; diflFerent species of fucus are the most 
remarkable, so that in some places immense numbers of impres- 
sions have been found. We met with examples of this kind in the 
grey marl and limestone in the vicinity of Alberona, in Capitanata, 
or in the red schistose marl on the banks of the little river which 
runs at the foot of the hill of Melfi, on the north-west side ; and in 
the same red marl heaped together, impressions of the lucus, 
Colle delle macine, are found near Lama in Abruzzo Citra. We 
frequently find, both in the marl and limestone, branched cylindrical 
concretions, more or less broken, sometimes more than six decime- 
ters in length and easily separated from the rock which contains 
them. We cannot doubt that they are formed from plants, and 
they ought probably to be considered fucoids. Small deposits of 
lignite are also frequent, among which it suffices to mention that of 
the Vallone della Salla, near Pagliari, to the south of Benevento, 
in which we have found the stems, leaves, and seeds of carbonized 
plants in good preservation.* It would certainly be of great benefit 
to science if the species of these plants were precisely defined ; we 
are not aware whether any one has as yet directed attention to 
this matter, or has published the results of his inquiries. We have 
not time for it, nor could difficult inquiries of tliis nature find a plac^ 
here. As to fossil animals, to rci)eat our former statement, if there 
are any, they are very rare. In some limestone strata in the 
vicinity of Gaeta, which probably belong to this series of rocks, we 
saw some very distinct impressions of Pccten, which did not apj^ear 
to us to belong to any of the living species of our seas. And in 
the limestone near Madonna di Macera, nortli of Melfi, we found a 
few fragments of marine shells, but we could not determine with 
certainty to what genera they belonged. From what has been 
now said, the difficulty of referring our fucoidal rocks to any 
fonnation of a determined ejioch must be very evident However, 
as they are subsequ(»nt to the Apennine limestone, and more 
ancient than the supcTcTctaeeous deposits called sub- Apennine, the 

* Breislak, notes this deposit in the * Pliysical Topograpliy of Campania.' 
FloR^ncc : 1708 V\\ 63, G4. 




THE SUB-APENNINE ROCKS. 193 

question to be decided is, whether they belong to the last of the 
cretaceous groups, or to the first of the supercretaceous. We do 
not know whether the question can be fiirther settled, nor do we 
consider it of sufficient importance to repay the trouble of a closer 
definition. 

Some, of these rocks have been confused with the supercretaceous 
deposits, others have been referred to the cretaceous or {giuras»ico) 
Jurassic period. In our opinion they all belong to the same formation, 
having a similar mineralogical composition, the same paleontological 
charactenstics, and a not discordant arrangement of strata. We con- 
sider them, then, as distinct fix)m the real supercretaceous deposits 
(which they rather resemble in mineralogical character), not only 
on account of the want of fossil animals, but, what is more import- 
ant, on account of the disagreement of their strata with that of the 
marls, and sub-Apennine shelly sand& We have already seen 
that the difierence between them and the cretaceous deposits, or at 
least those of the Apennine limestone, is still more striking, and 
therefore we are of opinion that the fucoidal rocks form a distinct 
system. 

27iird Series. — Sub-Apennine Eocks. 

The rocks of this series most frequently consist of marly clays, 
sandstone, limestones, and a particular conglomerate of large 
pebbles. The arrangement of these rocks is not so regular as 
those of the preceding series, the strata are not so distinct, and 
they are always found horizontal, or but slightly inclined to the 
horizon, so that they do not appear to have been disturbed from 
the primitive position in which they were deposited. The topo- 
graphical configuration of these rocks, which are often of such 
little thickness that we might even call them superficial, has no 
distinctive character. For example, lying over the cretaceous 
limestone of the Murge, they merely render the plain more 
uniform or level, which but for them would have had greater 
inequalities. In the midst of .the Apennines, or at the foot of 
these mountains, they form hills with a gentle descent somewhat 
level on the top. And if in any rare instance, as in that of the emi- 
nence upon which the city of Ariano is built, they have a more 

VOL. I. O 



194 LITHOLOGICAL CHARACTERS— CONGLOMERATEa 

elevated and developed form, it appears to have been occasbned by 
the ancient topographical conditions of the place hayingbeen changed, 
a great part of the rocks having been carried elsewhere, while tkej 
continued with those that remained. The snb-Apennine limestone 
is usually tufaceous in appearance, very friable, and almost entirelT 
formed of minute fragments of zoophytes and marine sheljs, many 
specimens of which are found enclosed in a complete state of pie- 
servation in the rock. This rock, which is most abundant in die 
province of Bari, we have never found in the heart of the 
Apennines. Sometimes it is not so tenacious, and not so lidi in 
fossils. The sandstones (arenarie)y are generally firiablet, and one 
might rather say were deposits of sand ; thus they are easily dis- 
tinguished from the compact sandstone of the preceding formation, 
called Macigno. They often enclose small pebbles of different 
kinds, which, gradually increasing in size and number, at last tann 
a conglomerate of large pebbles, of which there are amasDg 
deposits. The greater number of these pebbles are formed of 
limestone, often marly, of Piromaco which sometimes changes into 
Diaspore, and of very compact sandstone. There are some pebUes 
of granite and other crystalline rocks, which we can easQy und6^ 
stand came from the Macigno of the preceding formation, whidi, 
as we have seen, sometimes contains them in great abundance. 
From the other rocks of the same formation, or fix)m the Apennine 
limestone, they have undoubtedly obtained other kinds of pebbles. 
We may mention those of quartz and Piromaco, which often still 
preserve between two opposite surfaces the limestone in which the 
Piromaco had been imbedded in the form of little strata, precisely 
as we find it in rocks of the first series. Deposits of pure sand 
with small pebbles are met with everywhere ; but the large pebbly 
conglomerate is only found in moimtainous regions, or near th^n, 
whilst the Calcareous Tufa exclusively covers the plains. The argil 
then, which is always more or less marly, is habitually of a sky- 
coloured grey, and, owing to its plastic qualities, is much better 
adapted for pottery than the fucoidal argil. In Calabria, where 
there are extensive mountains of rock crystal, the sub- Apennine 
deposits occasionally manifest particular characteristics, owinw- to 
the mineralogical elements of the neighbouring mountains which 



BRECX31AS AND CONGLOMERATES. 195 

enter into their composition. One of the most beautiful examples 
is famished by certain conchiliferous breccia, in the vicinity of 
Coeenza, with fragments of granite, and a great quantity of mica, 
which at first sight one might say was formed of granite, and which 
might lead the unskilfal to think that they had found granite filled 
with marine shells like sedimentary rocks. The limestone of this 
series, whether tufiEtceous or compact, is more abundant beneath, or in 
the more ancient deposit ; whilst the argils and sands usually occupy 
the upper position whenever they are found with the limestone. 
As to the conglomerate of large pebbles, it* may be considered the 
most recent sub-Apennine deposit, as it is never found beneath any 
other kind of neptunian rock of this series. It is frequently found 
lying on rocks of the preceding series ; the conglomerate on which 
Bipacandida is built, and that on which the city of Lavello is 
foimded, furnish us with examples in the vicinity of the Vulture ; 
the latter deposit of conglomerate extends level for many miles, * 
jfrom the tavern of Bendina, to the northern district of the territory 
of LaveUo. The southern declivities of the Vulture which are 
included in the name Monticchio, are formed of deep deposits of 
the same conglomerate, which will by-and-by claim our attention. 
The cities of Venosa and Carbonara are also built on extensive 
deposits of large pebble conglomerate, the arrangement of which 
differs so much from that of the preceding instances, because it lies 
on conchiliferous sub-Apennine marl, which is distinctly visible 
near La Fontana de' trenta Angeli, little more than two miles N.N.E. 
of Venosa. The immense quantity of pebbles which are frequently 
found heaped together in the heart of our Apennines is an evident 
proof of the great diluvial action to which these regions were 
subjected after the deposition of the supercretaceous rocks. 
Abandoning the inquiry into the unknown cause of this catas- 
trophe, we may, with better hope of success, seek to discover 
whether it preceded the emergence of Southern Italy from the sea, 
or whether it was subsequent to it. Of these opinions, the 
second is peifiaps the more likely to be true, as no marine fossils 
have ever been found in the conglomerate of which we have 
spoken; and although we have never been so fortunate as to meet 
with any land animal remains, yet in the Mineralogical Museum 

o2 



196 PALAEONTOLOGY. 

of the Boyal University of Naples, there are some elephantB* tuskB 
{difm elefcmte), found near Chiaromonte in Basilicata, and an npper 
jaw with the molar teeth, belonging to the same class of quadrupeds, 
which was found last year near Chieti, to which fossils some 
pebbles are adhering, which lead us to presume that they had 
been dug out of the conglomerate. 

Sub-Apennine paleontology is distinguished by possessing many 
species yet existing in the Mediterranean Sea. The subject has 
been treated by Brocchi and Philippi, and several other notices 
have been published by Neapolitan writers. Meanwhile the 
question whether deposits are found with us, which belong to the 
lower supercretaceous rocks, otherwise called Eocene, in which 
fossils of species analogous to the existing species are much less 
frequent, needs further investigation ; and as we cannot conclusively 
determine it, it suffices to remark that the fossils of the supers 
cretaceous rocks of Fizzo, in the province of Catanzaro, mostly 
belong to lost species, and that the other deposits of Grargano 
manifest the same condition stiU more strikiiigly. 



PART 11. 



THE NARRATIVE AND FIRST DEDUCTIONS. 



CHAPTER I. 

THE REGION OF OBSERVATION — ITS SEISMIC HISTORY 
— OBSERVATIONS AT AND AROUND NAPLES. 



The seismic region to which this Report refers reaches in 
its most extended sense from Rome to Otranto, in a west 
and east direction, and from Gkirgano to Reggio in that north 
and sonth ; since within the whole of this surface — in feet, 
over the whole of the peninsula south of the parallel of 
42° — was the earthquake of the 16th December, 1857, more 
or less perceptible. In the more restricted sense, however, 
in which the seismic area is limited by the effects of the 
shocks having been forced upon the attention of the in- 
habitants, and left tangible traces of their advent, and thus 
determined the scope of the writer's observations and 
inquiries, it may be said loosely, to be bounded by a line 
stretching eastward from Sermoneta, at the head of the 
Pontine Marshes, to Foggia in Capitanata, and thence to 
the Adriatic; and comprehending all south of that, ex- 
cepting the peninsula of Otranto, east of a line between 
Monopoli and Taranto and the peninsula of Calabria Ultra, 
south of a line from Cape Suvero to Cape Colonna, thus 
embracing the surface between lat. 39"^ and 41° 30' and 
from long. E. 10'' 30' to long, E. 15^ or more than 200 
English miles by above 160. 



200 



PART OF SEISMIC BAND— AZORES TO CAUCASUS. 



This region forms part of the great seismic zone of the 
Mediterranean, stretching westward along the Atlas chain 
to the Azores, and eastward through Dalmatia, Albania, the 
Greek Archipelago, to Smyrna and Constantinople, and 
into Asia Minor, whence it bifurcates into the separate 
systems of Syria on the south and of the Caucasus on the 
north, and is one of almost constant disturbance. 

Its evil celebrity has become popular through the ter- 
rible earthquake of Calabria in 1783 ; but the frequency and 
extent of its earthquakes are but little known generally. 

Besides innumerable minor shocks at various points, and 
extending to greater or less areas, earthquakes are on 
record as having occurred within it in the following series 
of years, all of which have been of power sufficient to over- 
throw towns and destroy numbers of human beings, namely, 
in A. D. 



1181 


1509 


1602 


1654 


1702 


1770 


1230 


1523 


1609 


1659 


1703 


1777 


1282 


1537 


1614 


1660 


1706 


1782 


1343 


1544 


1617 


1662 


1731 


1783 


1349 


1549 


1620 


1670 


1732 


1784 


1446 


1550 


1623 


1683 


1743 


1789 


1448 


1551 


1626 


1685 


1744 


1805 


1450 


1559 


1638 


1687 


1746 


1806 


1454 


1561 


1640 


1688 


1753 


1807 


1456 


1594 


1644 


1693 


1756 


1812 


1460 


1596 


1646 


1694 


1759 


1814 


1486 


1599 


1652 


1697 


1767 


1818 



1826 
1832 
1835 
1836 
1841 
1847 
1851 
1854 
1856 
1857 



or 82 great earthquakes since the commencement of the 
twelfth century. 



ANCIENT AND RECENT ANTERIOR SHOCKS. 201 

Most of these are recorded in the Catalogues of Perrey, 
and in the General Earthquake Catalogue of the British 
Association ; but the particulars of many are only to be 
found in the works of local authors, such as Colosimo, 
Onofrio, Grimaldi, Lombardi, Battista, Don Arabia, Col- 
letta, &c., which are scarce and not to be consulted collec- 
tively out of Naples, 

As observed in all habitual seismic regions, the great shock 
of December, 1857, was preluded by several minor ones. 
In 1856 shocks are recorded by Perrey (* Catal. Ann. *) 
in January, March, May, August, October, and November, 
some of which embraced areas extending simultaneously to 
Naples, Melfi, and Cosenza ; and fully an equal number are 
said to have marked the succeeding year prior to December : 
the most important in either year, was felt chiefly at and 
around Salerno on the 12th Oct 1856, and seems to 
have escaped the usually extensive information of Perrey. 
The following notice of it occurred in the * Times ' of 16th 
Oct. 1856— 

"Earthquake at Sorrento, Oct. 12. — The following 
account of an earthquake at Sorrento is given by a corre- 
spondent : — * A few hours ago we experienced two shocks 
of earthquake more severe than have been felt in these regions 
for several years. A few minutes after two o'clock a. m. 
I was awakened by a sensation as if my bed were about to 
slide out of the window in front of me. From previous ex- 
perience I instantly became aware of what was taking 
place, and lost no time in collecting my family in the 
doorways of the sleeping-rooms, which are supported by 
very thick walls. The oscillations continued in rhyth- 
mical intervals of three seconds until I had counted four of 



202 PREVIOUS SHOCKS. 

them. After a state of quiescence — it might have been 
three minutes — the house began to reel confusedly, and 
then composed itself into another series of pendulum-like 
oscillations, in a direction from east to west, more pro- 
longed than the former. I noticed that I could count, with 
moderate haste, three for the advance movement, and 
three for the return. These were repeated five times, and 
accompanied by a rushing noise, as of a brewing storm, 
and an underground rumbling like distant thunder. In- 
doors the sounds resembled the straining timbers of a ship 
in a gale. The moon was shining serenely, and the column 
of white vapour was issuing from the sunmiit of Vesuvius 
calmly as usual, but the hurried prayers and sobbing 
ejaculations of the peasants in a neighbouring podere 
(farmstead), and the frightened baying of the watchdogs 
in the orange gardens, gave evidence of the terror which 
had just passed over the plain of Sorrento. By some the 
visitation had been expected. The weather had been very 
sultry for several days, and a peculiarly dense and ill- 
smelling fog had obscured the bay. The general alarm 
was very great, and most of the inhabitants of Sorrento 
rushed into the streets and open spaces. I have not heard 
that damage was done to any of the houses.' " 

The very day preceding this, 15th Dec. 1857, a severe 
shock was felt at Rhodes, indicating that very distant 
points in the same seismic zone were then in agitation. 

In recording from my note-books, &c., the facts ascer- 
tained, I shall now, for convenience, adopt the personal 
pronoun. 

The preliminary inquiry of a day or two at Naples 
decided the general plan of investigation to be pursued. I 



COURSE OP OBSERVATION CHALKED OUT. 203 

proposed to myself to search the heart of the shaken 
country firom the westward, then to pursue a southern 
track until I should have nearly reached its confines in 
that direction, and then (by another road, and further 
eastward if possible,) retrace my steps, and pursue a 
northern course until I reached its northern confines. 

I reserved for the results of so much of my examination, 
the determination of whether to pursue a direct eastern 
course, then firom the middle region, or to stretch farther 
north, and then observe the effects of the transverse chain 
of the Apennines upon the main earth-wave. 

Much interest attaching to the question of a permanent 
rise or &11 in the level of the land, at or after the shock, 
I made such observations as were practicable at and around 
Naples ; but none of these proving decisive, I resolved, be- 
fore turning to the eastward along the course of the Salaris, 
to go a little further south, and examine the coast and 
river mouths between Naples and the mouth of the Salaris 
and down to Psestum for evidences of any such movement. 

The narrative, therefore, will be given in the order 
nearly of the places visited, condensing together ob- 
servations, &c., made at different times when the same 
places were visited twice. 

Naples, City. — The following is the official notice of 
the shock, translated fi-om the *Giomale Reale* of I7th 
Dec. 1857 : — '* We have received the following letter fi-om 
the director of the Astronomical Observatory at Capodi- 
monte — * Sir— I hasten to inform you that last night at ten 
minutes after ten o'clock (tempo meridiano) a shock of 
earthquake occurred which lasted about four or five seconds ; 
two minutes afterwards another shock of much greater in- 



OFFICIAL NOTICE— OBSERVATIONS AT 



tensity oocorred, which lasted aboat twenty-five seconds. 
They were both undalatory, and proceeded from the soath 
to the north. The severity of the second shock was apparent 
from the fact, that two pendolom clocks belonging to this 
Observatory which oscillated in the plane of the prime 
vertical, were stopped, (three others however, were onaf- 
fected). The foundation of the tower in which oar 
equatorial instrument is placed also sustained injury. We 
were also sensible of three successive but slight sfaodis, 
at three and at five o'clock in the morning (i. e. of the 
17th; ") (See Appendix, No. 3.) 

On visiting the Observatory I was unable to converse 
with the astronomer, Signor de (Jasparis, who was anwell, 
bnt was shown over the establishment and my inqniriea 
answered, by Signor Nobili, filio. 




Fig. 111. Fig. lis. 

In the transit room (Fig. Ill) {t t being the two 



THE OSSERVATORIO, CAPO DI MONTE. 205 

instruments), are two clocks, cc, whose pendulnms vibrated 
in the plane of the prime vertical, and showing sidereal 
time. These were both stopped, but, according to Signer 
de Gasparis, at different moments, and each at an unequal 
period after the shock, owing to their structure, so that 
nothing could be concluded as to the precise moment of 
the first shock from them. I could not ascertain upon what 
precise data the moment stated in the Giornale as above, for 
the occurrence of the shock was based, and from other facts 
entertain some doubts as to its precision. 

I found by measurements that a moment in the line 
of the meridian, and therefore transverse to the plane 
of vibration of less than 0-5 inch would have been suffi- 
cient to have stopped either of these clocks, unless the 
contact with the case and pendulum so produced, had been 
instantly removed by a movement in the opposite di- 
rection, and before time were given to destroy by friction 
the momentum of the pendulum. 

In the Salle Centrale, which is also the library of the 
Observatory, and leads by a winding stone staircase at one 
end, to the top of the tower where the equatorial is fixed, is 
a third clock, showing Naples mean time, whose pen- 
dulum, an extremely heavy one, oscillates in the plane of 
the meridian, which was not stopped. A movement of 
the pendulum bob of 0*625 inch transverse to the plane 
of oscillation would have stopped this clock. 

These clocks are not screwed to the walls, and neither 
they nor any of the other instruments had suffered damage 
or derangement. 

Two chronometers lent by the Lords of the Admiralty, 
and brought with me from England, going Greenwich mean 



206 FISSURES AT THE OSSERVATORIO. 

time, were compared with the time at the Observatory, and 
one was found to have been slightly deranged by the 
railway journey. I had deemed it probable, that by the 
co-operation of some Neapolitan savant, I should be able to 
get measures of horizontal surfece transit velocity of the 
earth-wave, in some of the slight shocks said to be still 
continuing. The uncertainty of their recurrence and 
difficulties as to finding any Neapolitan co-observer, ren- 
dered this impracticable. The chronometers were, however, 
of much service to me in the interior of the country, one of 
them having been adjusted to Naples mean solar time 
before I started. 

The Salle Centrale has its length in the direction of the 
meridian. At one end a doorway, c (Fig. 112) leads to 
a stone winding staircase, descending one deep story, 
and ascending to the equatorial, which is thus placed 
on the top of a cylindrical tower, formed of a central 
solid cylinder of masonry of about 6-5 feet diameter, 
the steps about 4 feet wide, and the outer cylindrical 
wall of about 3 feet in thickness ; the total height from 
the ground to the floor of the equatorial being about 
70 feet. 

Fig. 113 is a section across the Salle Centrale at a 6 
(Fig. 112), showing the interior elevation of the end next 
this tower. From the centre of the lintel of the doorway 
at Cj a nearly vertical fissure, open 0*20 inch at bottom, 
extends upwards, becoming evanescent at about twelve 
feet, and its plane is in that of the meridian. Its conti- 
nuation downwards can be traced from the centre of the 
sill of the doorway also. 

A second fissure at B, occurs right through the outer wall 



FISSURES AT PALAZZO LIETI. 207 

at right angles to the former, or east and west, and extends 
about ten feet up and down, (commencing where the wall 
had been weakened by an aperture now built up) 
and vertical-width 0'15. It is higher up the tower 
by five feet, than the fissure C at its mid length. The 
inertia of the central core of masonry here is enormous 
in relation to its base; and to that, no doubt, is due 
these fissures, the only two formed in the whole building, 
which is solidly and well built of rubble and ashlar 
masonry. 

The fissure C appears to have been produced by the 
spiral lapping of the staircase round the central column 
(through which the push of the latter was transmitted to the 
cylindrical shell) having prevented its vibration as a simple 
pendulum in the plane of the shock, or near it, and induced 
a movement of conical vibration. The movement in- 
dicated is one nearly from south to north by compass. 

Several other buildings in and directly around Naples 
were fissured, but none were thrown down. Amongst 
those which I examined were Messrs. Turners' bank, in 
St. Lucia, the Tribunale, and several palazzi, amongst the 
latter the Palazzo Lieti, in the Toledo. In no case, how- 
ever, could I find that the fissures had been originated by 
the shock of 17th December : they were all pre-existent, 
and due chiefly to settlements, but had all been slightly 
enlarged by the shock. 

The derangement at the Palazzo Lieti was so consider- 
able as to demand prompt measures to prevent the fidl 
of one wall of the interior court, by building up solidly, 
a huge arched porte-cochere that had jrawned beneath it, 
and was about twenty-four feet span, with a new wall and 



ALARM IN NAPLES AT THE SHOCK. 




smaller arcb as in dotted lines Fig. 114. The boilding, 
consisting of fonr lofty storeys, and nearly eighty feet in 
height, I fotrnd had been fissured from settlements for a 
length of time ; but the shock had been 
sufficient to shake downwards the cen- 
tral mass of the wall between c and e, 
and to widen all the old fissures, which 
were now three-quarters of an inch 
wide — those c and c widest at top, B 
widest at bottom — evidencing dearly 
the nature of their production. 

This, 1 found, was considered the most 
formidable example of injury to baild- 
ings occurring in or around Naples. 
In no case, except at the Observa- 
tory, was I able to remark an original fissure in any 
well-built and sound structure. 

The actual range of movement at Naples must have 
been small and far from violent. The amount of alarm 
produced generally by the shock was, however, sufficiently 
great to cause almost the whole population of the city to 
spend the remainder of the night of the 16th December in 
the open air, in carriages, around lai^e fires in the streets, 
&c. The principal source of alarm described by most 
persons was from the creaking and straining noises of the 
timber work of the heavy floors and roofe, and the rattling 
of the windows and doors. A large portion of the popu- 
lation spent the succeeding night of the 17th December 
also in the open air, or in parading the public places. It 
was manifest, however, that much of this on both nights 
arose from the excitement and newsmongoring tendencies 



SENSATIONS OF THOSE AT NAPLES. 209 

of the people, who made a sort of " festa" of the occasion, 
and but little from actual terror except at the first moment. 

From some persons of observation and discretion, I col- 
lected, their own perceptions of the phenomena. 

A young English lady, residing in Santa Lucia, of 
much intelligence and observation, was at tea with some 
friends, sitting round a table whose length was nearly E. 
and W. by compass. Her attention was first arrested by 
a transverse movement of the table sliding back and for- 
wards about an inch each way upon the waxed tiles of the 
floor. This she at first thought arose, from some of those 
who sat with her, but on casting her eyes upwards, on 
hearing the floor above creaking, she saw that a lamp 
suspended from the centre of the ceiling was oscillating also. 
Earthquake, which she had experienced elsewhere, then 
occurred to her, and she noticed carefully both the direc- 
tion in which the lamp swung and the arc of its oscillation. 
She set the lamp itself again swinging for me, above the 
same table, in as precisely the same direction and to the 
same extent as possible. The direction I found to be 
8° 0' E. of N. by compass, and the summit of Vesuvius 
bears 110° E. of N. from the front window of the room 
(which was on the second floor from the ground). The 
chord of the arc of vibration was 10| inches, and the lamp 
makes thirty double oscillations per minute by the watch ; 
it weighs about 12 lbs. 

Her sensation of the shock, was of a small, rapid, recur- 
rent, movement, forward and back, perfectly horizontal, 
without any undulating motion ; then a cessation for 
two or three minutes (as estimated), and again a renewal 
of the same motions ; after which all was quiet. 

VOL. I. p 



210 1)R. LARDNER'S ACCOUNT. 

The late Dr. Lardner was residing with his family at the 
H6tel des lies Britanniques, in Chiaja, and was at the time 
in a " salon " upon the third floor. His impressions were of 
a larger amount of oscillation, and with more or less of 
undulation. He has recorded them (with, perhaps, a little 
excess of colouring) in a letter published in the Times of 
29th December, 1857, under date 19th December. He 
obligingly went with me to the "salon" at the hotel, 
wherein we found a large and ponderous chandelier hang- 
ing, of which he had observed the swing on the night of 
shock. He set it again in movement in the same direction 
and to the same extent. 

This chandelier weighed 190 lbs. avoirdupois, hung (to 
the lowest point) 8 feet 9 inches from the ceiling, and by 
trial made 26^ double oscillations per minute. 

According to Dr. Lardner, it commenced to swing in an 
arc of about 24 inches chord, and in one plane, the azimuth 
of which I found to bear 13° 0' E. of N., the Point of 
Pausillipo bearing 130^ W. of N. from the front windows 
of the room. This vibration rapidly became elliptical, the 
major axis diminishing from 24 inches untjl it became about 
12 inches; when the lamp continuing to vibrate as an 
ellipto-conic pendulum, was stopped by Dr. L., as he 
stated, both to appease the alarm of his family and to 
enable him to observe the efiect of a renewed shock. The 
time by his watch was 10^ 15' Naples mean time, but he 
could not guarantee that the watch was perfectly right, 
though a good one. 

His sensation of the first movement was of a short, 
jarring, horizontal oscillation, that made all doors and 
windows rattle, and the floors and furniture creak. This 



SIGNOR GUISCARDI. 211 

ceased, and after an interval that seemed but a few seconds 
was renewed with greater violence, and, he thought, with a 
distinctly undulatory movement, **like that in the cabin of a 
small vessel in a very short chopping sea." It was suflBcient 
to demand a certain amount of attention and eflfort, on the 
part of those standing up, to maintain their equilibrium. 

Signor Guiscardi, a highly intelligent observer, educated 
as an architect and civil engineer, and well acquainted 
with physical science generally, had just retired to bed, 
when his attention was aroused by the first movement, 
which he describes by a little diagram, as simply a short 
sharp, jerking movement forward and back, thus : — 

within narrow limits, and lasting, as he supposes, about 
five to seven seconds ; then a total pause of some seconds, 
and then the former movement recommenced with rather 
more violence, and in this sort of order — 

— M >:( >.^(— —>.^ >•< >.^— 

an interval of almost complete rest occurring between two 
fits ; this concluded the earthquake. He did not perceive 
any undulatory ^/-v.>^-v^.>^>s,-^^-s movement, nor any 



movement up and down. 






and is certain, the movement 



(as not unfrequently asserted in Naples) did not commence 
with a movement up and down. The " pendules " in his 
rooms, having a general E. and W. plane of vibration, were 
stopped at 10^ 10' Naples time, but he cannot guarantee 
their accuracy as to time. 

I was not enabled to gain any additional facts of im- 
portance, from conversation with Signor Capocci, ex-pro- 
fessor of astronomy, or with Signor Palmieri, professor 

p 2 



212 SICKNESS FELT BY ONE PERSON. 

of physics. Both agreed that the direction of wave move- 
ment was from S. to N., with more or less of an eastern 
or western swerve from the magnetic meridian. 

There was no material alteration, either in inclination or 
declination of the magnetometers noticed ; but Professor 
Palmieri's views are, that every eruption of Vesuvius and 
Etna, and probably every earthquake, is accompanied by 
great electrical disturbance, which, he supposes, may affect 
the magnet. His seismometer at the Observatory upon 
Vesuvius was affected by the shock. The magnetic decli- 
nation is very variable, both in short periods of time and 
for adjacent localities in and about Naples, and he thinks 
continually alters with the state of Vesuvius. I myself 
ascertained the declination in St. Lucia to be only 9° west 
in one spot ; but blocks of lava used in building, pavement, 
&c., all more or less magnetic, make such observations very 
uncertain. The mean declination, however, for Naples, I 
obtained from the Observatory = 14'' 30' west in February, 
1858 ; and this agrees with the monthly printed determina- 
tions of the Royal Marine Observatory at Naples. 

The whole of these five observers above mentioned 
agreed, tliat the shock at Naples was not attended with 
any noise whatever, either preceding, during, or succeed- 
ing the movement. 

One gentleman only in Naples described to me sensa- 
tions of sickness felt by him during the shock, which he 
first perceived while playing cards. In his case my im- 
pression was, that the affection was due to nervous excite- 
ment and alarm only. Conversation generally with persons 
of all classes in Naples, only tended to increase on my part 
the caution necessary in attempting to found any conclusion 



FIODO'S CLOCK. 213 

upon statements of physical facts, so exaggerated and 
often inconsistent, as those in common circulation, though 
unaccompanied by intentional deception. 

Signor Fiodo, Yico Baglievo, Strada Toledo, chrono- 
meter-maker to the Neapolitan Marine (who executed the 
needful repair and new rating to one of my English 
chronometers), I found a man of great intelligence, discre- 
tion in observation, and accuracy of thought, and from him 
T derived some of the most useful facts obtained at Naples. 

In his "atelier" he has a regulator clock, with a heavy 
gridiron pendulum vibrating seconds, and, as I found, 
oscillating in an azimuth 20° E. of N. by compass. Resting 
upon the bottom of the clock-case, which is of polished 
chestnut, he had long placed a small steel anvil or parallelo- 
piped of the exact dimensions shown and figured in Fig. 115, 
five sides of which are smooth, but black as when forged, 
and the sixth polished. This stood on edge, the polished 
side being next the pendulum (and behind it as one faced 
the clock), and the plane of this side, parallel with that of 
the oscillation — the polished surface being by measurement 
exactly 0*276 inch horizontally from the adjacent side of 
the screw at the bottom of the pendulum bob. The chord 
of oscillation of the pendulum measured at the screw was 
= 1*87 inch, and less than the parallel dimension of the 
steel block. A small amount of transverse movement, 
therefore, would be sufficient at any time to stop the clock 
by bringing the screw of the pendulum into contact with 
the face of the steel block. 

On the morning of the 17th December, 1857, Signor 
Fiodo found this clock stopped, and the screw of the pen- 
dulum in contact with the south end of the steel block. 



TIME BY PIODO'S CLOCK, 



which had been shifted from its place by the momentum 
of the peadulom, as in Fig. 115. 




I shall recur to the inferences derivable from this in 
Part III. It is sufficient here to remark that the direction 
of wave movement indicated is one approximately 6° E. 
of N. The clock was going (tempo meridiano) or solar time 
for Naples, and was on the evening of the Itith December 
true to time within an error of 0*5 socond. It had been 
stopped at 10'' 13' 26" p.m., which was therefore the 
time of the first shock at Naples, within less than half a 
second the error of the clock (slow), + the minute fraction 
of time due to the increased semi-arc of vibration. 

There were several other clocks, some with pendulums. 



FISSURES IN TUFA AT PAUSILLIPO. 215 

but making half and quarter seconds beat, in Signer Fiodo's 
establishment, oscillating in directions approximating to 
the meridian, and to the prime vertical, but none were 
stopped, and on examination I found them not circumstanced 
so as to have been so. 

I verified with care all the dimensions and particulars 
of the regulator that was stopped, and have not the smallest 
doubt either of the good faith upon which the facts taken 
from Signor Fiodo rest, or of the exactness of the con- 
ditions as obseiTcd by him, and the dimensions, &c., as 
taken by myself. 

On passing into the Naples end of the tunnel (or grotto) 
at Pausillipo, I remarked several fine, keenly-drawn lines of 
nearly vertical fissures, in the perpendicular banks of yellow 
tufa at the right-hand, or S.E. side of the entrance, which 
appeared recent. The light, however, was not sufficient to 
enable me to decide. I therefore returned early the follow- 
ing morning, and by clear sunlight made a minute exa- 
mination of those cracks (the occurrence of which no one 
had remarked as £a.r as I could learn). I satisfied myself 
that they were very recent, that they were not due to any 
settlement or alteration by gravity alone, of the banks, nor 
due to any artificial work, or excavation. 

The keenness of their external lips or edges, the absence 
of dust, cobwebs, or insect or vegetable life, within or across 
them, and their narrow and uniform breadth of opening 
about 0*2 inch, their general parallelism, and, above 
all, their direction in azimuth, with relation to the form 
and direction of face, of the bank, and their verticality, 
convinced me that they had been produced by the shock 
of the 16th December, and were due to the inertia of the 



216 GENERAL WAVE-PATH AT NAPLES. 

enormons bank of tufa through which the tuunel has been 
cut. I found their direction to be such, as indicated dis- 
tinctly a wave-path and direction, of between N. 20° W. 
and N. 38° W. The last extreme appeared to me doubtful, 
and as only derived from one cleft. I am disposed to 
adopt the former azimuth only. 

Upon the whole, the indications of wave-path at Naples 
are meagre, though not indistinct, nor discordant. They 
vary between the limits of N. 13° E. and N. 20° W., or, 
omitting Pausillipo wholly, vary between N. 6° E. and 
N. 13° E., and comparing all the indications, seem to 
give a resultant path of, N. 6° to 8° E. as the most trust- 
worthy. 

This appeared to point to a focus somewhere at sea, 
beneath the gulfs of Salerno, or Polycastm a first im- 
pression that became not a little puzzling, when brought 
into contact with the facts, as they developed themselves in 
the interior provinces, and at first, for a day or two, 
almost caused me to despair of being able to trace out 
the true focus at all, the fresh evidence as collected appear- 
ing to be quite conflicting ; and it was not until after I had 
found reiterated proofs of an inland focus, that could not 
connect itself directly with Naples, that the solution of the 
diCBculty began to appear, in showing the shock at Naples 
city, to have been merely a reflected and refracted one. 



CHAPTER II. 

PERMANENT CHANGES OP LEVEL ACCOMPANYING 
EARTHQUAKE — THE THEORIES OF 8ERAPI8. 



So much interest attaches to precise observations, as to 
permanent change of level of the land, occurring at the 
same time with earthquakes ; and this object having been 
urged upon my attention, by my friend Sir Charles Lyell, 
before I left England; I therefore gave the question of 
whether any such change had attended this earthquake 
very careful investigation, and I may say, have examined, 
as to it, the whole coast at various points, from north of 
Pozzuoli to Psestum. I found the almost universal opinion 
at Naples was, that an elevation of some inches around the 
whole bay, varying at diflferent points, had taken place, 
and the circumstantiality, with which intelligent persons 
residing upon the shore, pointed to apparent proofs of 
their impression, demanded much caution. Professors 
Capocci and Scacchi, with Signer Guiscardi, doubted the 
exisifence of any change of level, but could give no facts 
either way. All the evidence presented to me, was based 
upon references to assumed changes of tidal level. 

The English lady at St. Lucia, before referred to, pointed 



218 



A QUAY AT NAPLES. 



to a sloping quay bench (Fig. 116) opposite her windows. 
She had always remarked, that, at high water, the tide 
covered to the point c, or an inch or two above it, prior to 

Fig. 116. 




JLml tfM9atKrSF»hJ^. 



Fig. 117. 

the 16th December; but since that, the high-water level had 
been permanently about five inches beneath the arris of the 
quay at ^, giving a diflference in level of from nine to twelve 
inches. To test this I examined the water level daily at 
the hour nearly of highest tide, and for four days found 
the highest tide-mark as at 6 ; but on the next occasion of 
observation it was not only at c, but some inches above it 
The diflference was simply due to the oflf or on shore wind. 

It would be tedious to record several other observations 
round the bay of like character. 

On visiting the Temple of Serapis, at Pozzuoli, where the 
notoriety it had already acquired on this point, and the daily 
attention given to it, presented the best chance of decisive in- 
dication, no evidence whatever could be found of change of 
level. The " gardien " of the place, however, on being ques- 
tioned as to whether he had observed any change of level, at 
once directed our attention to the base of one of the wonn- 
eaten columns, and stoutly aflRrmed that the level of the 



OBSERVATIONS AT SERAPIS. 219 

water which was then standing at a (Fig. 117), had, directly 
after the shock of December, fallen to 6, equivalent to a 
rise of the temple of 7 inches, but that, since that time, 
the water had gradually returned to its former level, i. e. 
the land had sunk again. 

He denied that the diflference could be due to variability 
in the sea level. The utmost limits of disturbance by wind 
or tide within the sheltered valley of the ruins being, ac- 
cording to his stated experience, far within 7 inches. 

I could not find, that any man of science in Naples, had 
ascertained what these limits of aqueous disturbance were, 
and on my return to the city (from the interior), I took the 
occasion of a severe gale of wind in shore — the " Garbino," 
from the S.W. — and at the presumed time of high water, to 
visit the temple again, in company with Signer Guiscardi, 
when I found the water rather above the level of the sill 
of the entrance iron gate, and fully 22 inches above the 
level of the 5th February, and it had been nearly 3 inches 
higher about two hours previously. 

It is obvious, therefore, that any deduction whatsoever 
as to levels, whether of elevation or of depression, based 
upon the tidal level of the Mediterranean on this coast, 
cannot be depended upon, within the limits of 18 inches 
or 2 feet at the very least ; and several of the speculations 
as to minute oscillations of level of the Temple of Serapis so 
based must henceforward be received with doubt. 

Impressed with this fact, in which I found that Professor 
Capocci and Signer Guiscardi coincided with me, and with 
the extreme value to physical science, of possessing, in this 
instable region, some definite and unimpeachable standard of 
level, 1 addressed a formal letter, upon my return to Naples 



220 NEW VIEWS AS TO CHANGES 

from the interior, to the government of his Majesty, the 
late king, suggesting the importance, of having an accurate 
line of levelling run through to Naples, from the sill of the 
front door of St. Peter's, at Rome, which may be presumed at 
present as the best, if not an invariable datum point, and the 
difference of level marked upon bench marks at and around 
Naples. (See Appendix No. 4.) The work could be per- 
formed with ease and little cost by the officers of the " Ponte 
e Strade," going along the high road between the capitals. 
I regret to say, however, that it was intimated to me, at 
the Ministry of the Interior, that this despotic government 
objected to entertain suggestions from foreigners, even as 
to matters of science; and the work, which could then 
have been accomplished with facility, in connection with 
certain railway surveys in progress, remains, and is likely 
to remain unperformed. 

While the limits of error as to levels deduced from the 
sea, affect all minute questions of rise and. fall of Serapis, 
they do not touch the great change of level, as evidenced 
by the celebrated columns ; but they appear to me sufficient 
to destroy the force of the conclusions of Niccolini and 
others, as to oscillatory changes of level of small extent. 

The evidence of elevation, of the whole building since its 
original construction appears to me irrefragable ; but not 
so that upon which the supposition of its subsidence first, 
after its erection, and previous to its elevation are based. 
The argument for subsidence, rests upon the improbability 
that the level of the floor of the building was originally 
designed and constructed, below that of the mean tide of 
the Mediterranean. Now it appears to me that the proba- 
bility runs just the other way. Archaeologists appear to 



OF LEVEL OF SERAPIS. 221 

have settled/that the so-called Temple of Serapis was not 
a temple at all, but a public bath, a conclusion that forces 
itself upon the mind of any untheoretical observer of the 
general architectural structure of the place. If a bath, 
nothing is so probable, as that its level should have been 
fixed with reference to the sea, such that sea- water would run 
in, or command the baths, in a place where there appears to 
have been no fresh water except that of the thermal spring. 
The possible objection to this, that there would then be no 
drainage for the waste water of the baths is met by the fact, 
that the dry and porous subsoil, consisting of 12 to 20 feet 
of tufa, lapilli, and scoriae, would soak away any amount of 
water, if simply discharged into a pit sunk in it, below the 
level of the baths, a method of drainage actually practised 
from a remote age to the present day. A considerable 
district of Paris at present discharges the whole of its 
sewage into such a "puit d'absorption." 

The land at the existing level of the terrace called 
La Starza, upon which the temple was built, is in rapid 
and constant process of marine degradation at present ; so 
much so, that unless artificial means be soon taken to 
prevent its inroads, the sea will in another half-century 
probably, have swept away the whole temple (so called). 

It therefore was probably very much more inland when 
first constructed, and was probably built either in some 
natural depression, of 10 or 12 feet below the sea level, or 
in one excavated to that depth, by a race whose burrowing 
tendencies are revealed by many of their buildings, in all 
directions around. If much inland, there was doubtless a 
sufficient mass, though of porous material, between it and 
the sea, to be water-tight ; but if, as more and more of this 



222 SERAPIS CONTINUED. 

became removed, the sea-water percolated the bank univer- 
sally, at the seaward side, it could no longer be kept out 
from the building, and the place would have been aban- 
doned as untenable. 

The water of the sea would then stand permanently 
at a level with the highest line of testaceous perforations 
of the limestone columns, say about 20 feet above the level 
of the present floor, assuming that the general level of La 
Starza loas then about 8 feet under what it now is, and that 
the floor was originally founded 12 feet below the sea 
level. 

The channels or ducts that had before brought the sea- 
water to the baths would also bring the young testacea, 
and preserve sufficient change for their healthy existence. 
If, subsequently, the land bearing the so-called temple upon 
it, were gradually elevated about 8 feet, resting at about its 
present level, we have sufficient to account for the phe- 
nomena observed, without having recourse to, several suc- 
cessive depressions and elevations. 

Elevations are common, and obviously part of the esta- 
blished cosmos of the earth's surface, but depressions, due 
to subterraneous forces, appear exceptional and rare, and 
especially doubtful, close to volcanic vents. Land-slips and 
aqueous erosion, marine and of every other sort, appear 
the established agents for depression of surface, acting in 
antagonism to the former. Indeed, proofs seem wanting, 
of any such thing as recurrent oscillation of level, of any 
known tract of land within the historic period, traceable 
in both directions of movement, to subterraneous agency. 

To the view here advanced as oflfering the simplest and 
most probable solution of the Serapis problem, it may be 



ITS FOUNDATION IS MOVING SLOWLY DOWNWARD. 223 

objected, that the adjoining ruins of the Temples of Neptune, 
and of the Nymphs, are some feet under water, and that the 
arches of the so-called Mole of Pozzuoli, are covered above 
the level of the springings. The levels of these two latter 
temples will not accord either with the presumed depression 
or elevation of Serapis, and may hence be made to argue as 
much against, as for the oscillatory view ; and as to the 
arches and general structure, of the so-called mole now 
deeply immersed, I am satisfied that it never was built for 
a sea mole at all, and that the whole of the arches were origi- 
nally built on dry land, and for other purposes. It would 
be a work of no small difficulty, to construct these piers 
and arches in the open sea-way, where their remains now 
stand, with all the aids that modern engineering afford: 
and without the diving-bell we may safely affirm that they 
never could have been built in open searwater. They, 
further, are of dimensions and construction, that no Roman 
or any other architect would have adopted for a marine 
mole. 

How, then, came they immersed as they are ? It appears 
to me that they, and the incoherent tufaceous land, that 
sustains them and these temples, are now, and have long 
been, in gradual process of insensible land-slip downward 
and seaward, by the continual removal by tidal action of the 
loose material, from the foot of the submarine talus, which 
the soundings prove, to be outside them, in the roadstead, 
hence unequal subsidence, but always greatest where nearest 
the sea-shore. And this view is strongly corroborated by 
the fact, that all the standing columns at Serapis lean some 
inches out of plumb to seaward^ and that the ivhole floor 
of the place is waved arid uneven, and with a general out- 



224 THE MARINE MOLE— ROMAN ROADS. 

of -level slope to seaward also, as though the whole mass 
stood upon a base of loose soft material that was graduallj 
settling and going seaward from the effects of subUttoral 
erosion. This seems also to be the solution, of the instances 
of the Roman roads, under water between Pozzuoli and 
Baiae, and the Lucrine Lake. 

Moreover, if Serapis had been ever depressed to the 
extent required, then this so called marine mole must have 
been equally so ; but it is quite obvious to an engineering 
eye that were the arches, upon the piers as now standing, 
depressed but a few feet more, so as to receive the fiill stroke 
of the waves in storms, or the entire impulse of the moving 
superficial column of the sea, they would have been over- 
thrown long ago. They only stand because they never yet 
were wholly under water. 

The general importance of questions of permanent ele- 
vation or depression, and their intimate connection with 
earthquake phenomena, will, I trust, be deemed sufficient 
ground for this digression, upon the much-discussed Temple 
of Serapis. 



CHAPTER III. 



EXAMINATION ROUND THE COAST AS TO PERMANENT 

CHANGES OP LEVEL. 



On my way southwards, I received an introduction from 
the Intendente of Salerno, to Signor Palmieri, an engineer 
of the Ponte e Stradi, whom I fell in with at Eboli. In 
conversation he stated his opinion that since the shock of 
December 16th, the sea level all round the west coast, has 
been lower, i.e.j the land higher than before. He sus- 
tained this, by reference to a quay or wharf wall not very 
long since erected by himself at Amalfi on the shore of 
the Gulf of Salerno. The level of the sea at half 



fti?^yigYV'**y 




t : > -: 






Fig. 118. 



tide, he said, was always previously at a (Fig. 118), 
or coincident with the top of the timber work, at 



VOL. I. 



226 QUAY AT AMALFL 

the toe of the sea wall, but then stood about one paha, 
or 10 '3 8 inches English, below it at b. I examined into this 
on my return northwards, but the account of my observa- 
tions will be best given here. On the 27th of February, 
1858, at the lowest point of low water, of the afternoon 
tide at Amalfi, I found the sea-level to be 11 inches below 
the top of the cap sill or longitudinal timber, over the tops 
of the piling at the toe of the wharf wall, (which has a 
hollow parabolic curved sectional contour) ; that is to say, 
about half an inch below the half-tide level 6, according to 
Palmieri. Some loose volcanic sand, was heaped up at the 
foot of the wall above the permanent gravel of the beach 
beneath. Within a few hundred yards, I was able to find 
a sheltered nook between some rocks, where I noted the 
usual rise of tide, by the weed marks, to be 17 to 18 inches, 
and that high spring tides rose occasionally about 4 inches 
more. 

I recurred to this spot at high water of the same tide, 
and although having to use a lanthorn, and a little wind 
having sprung up, I was yet able to ascertain a rise of tide 
of 16 inches. Returning to the quay wall, I found the 
water there, too agitated for direct observation ; but referred 
to my adjacent tide gauge, the quiescent level of high 
water would then have been, 5 inches above the top of the 
cap sill, or at d, and with an 1 8 inch tide, 7 inches above 
same; or at high springs, about 11 inches above same. 
So that, the half-tide level is still in reality, just about the 
level of the top of the cap sill at a, as fixed by Signer 
Palmieri before the earthquake, and no change of level 
of the land has taken place at this point of the coast. His 
erroneous conclusion, must have arisen, I presume, from his 



POZZUOLI TO AGROPOLI. 227 

having mistaken at the time of observation, the periods of 
high, and of low water. 

I also examined the coast carefully to the eastward of 
Torre del Greco, and to where the railway branches off to 
Castellammare, and where some of the firm lava streams 
from Vesuvius, have run into the sea, and afford the best 
natural marks as to tidal level that the bay presents, but 
was unable to find any evidence of recent change of level 
of the land. 

I also examined the quays and beach at Salerno, the 
mouth of the river Vicentino, which falls into the Gulf of 
Salerno, S. E. of Monte Corvino, and the beds of the rivers 
Tusciano and Salaris, in the great plain of Paestum, with 
the same negative result. 

At Paestum, the proprietor of the soil, who is also the 
appointed guardian of the antiquities of the place, was at 
home at his " Casone." He was perfectly familiar with 
every feature of the shore line, from the ancient city down 
to Agropoli, and had recently passed along it, but had 
remarked no changes since December 16th, 1857; though 
quite alive to the question of rise and fall of the land. 

I conclude, therefore, that there is no evidence whatever 
of any permanent change of level of the land in con- 
nection with this earthquake, upon the west coast from 
Pozzuoli to Agropoli, and it is not conceivable that there 
should be any, upon the Adriatic coast, where the shock 
was only perceptible. 



q2 



CHAPTER IV. 

JOURNEY SOUTHWARDS — AMALPI — SALERNO — VIETRl 

LA CAVA — PLAIN OP PJESTUM. 



I NOW recur to my journey southwards. At Torre del 
Greco, Resina, and throughout the whole seaboard of the 
Bay, the shock was felt as sharply as at Naples ; and gene- 
rally over the whole plam of the Terra di Lavoro, in a 
direction from south to north : at Ottajana, to the south- 
east of Vesuvius, and close under the mountain, more than 
usual injury was done. The church of St Michael was 
largely fissured, and that of St. Johannes Battista also. 
I did not visit that town, but an inhabitant, whom I met 
elsewhere, stated that the direction of shock was generally 
felt from south to north, but also seemed to come from 
Vesuvius, and the like facts were stated as to the village of 
Somma. Small and unindicating fissures were to be found, 
in the older and worse built houses, &c., everywhere. At 
Torre del Annunziata, the west facade of the church, is 
largely fissured in directions clearly indicating a wave- 
path, not far from south to north. Ancient fissures from 
former earthquakes at lower levels are visible in its walls. 

At Castellammare, deduced from, not very well-defined 
fissures, the wave-path varied from 12° W. of N. to 
6° 30' E. of N. 




SORRENTO TO AMALFI. 229 

At Sorrento Point, the direction of wave-path was 
described to me by several intelligent observers resident 
there at the time, to have been from S. to N., or very 
nearly so. I could not visit myself that locality. 

In Pimonte, also, the facade of the Chiesa Madre was 
fissured, and part of the roof thrown in. At Sigliano, 
some houses were overthrown. At Gragnano, on the slope 
above Castellammare, a great many poor buildings were 
greatly shaken, as was also the case with all the villages, 
upon both the north and south sides of the mountainous 
peninsula, terminating with Punta della Campanella ; but 
in the island of Capri, directly south of Naples, and but 
a few miles from this cape, the shock was scarcely per- 
ceived. 

On the south side of this peninsula, Tramonte, Minori 
and Majori, were fissured, but uninstructively, from the 
character of the buildings. At Amalfi, the shock was 
alarmingly felt. The doors and windows rattled for ten or 
twelve seconds at each of the two shocks ; but no injury 
occurred to any of the buildings, which are generally of a 
substantial and well-built character of masonry. The 
Padrone of the H8tel des Capuchins, and also the chief 
apothecary of the place, were able to point out to me 
separately, the directions in which they perceived the 
shock ; both statements closely agreed in pointing out an 
azimuth, which proved to be 133° W. of N. ; ie., from a 
S. W. to N. E. direction ; and several facts indicated the 
occurrence of an orthogonal shock here, and at Atrani. 
The? heard no noise. 

The line of coast here is nearly E. and W., and so is the 
face of Palmier i's quay wall. 



230 FORMER LARGE ELEVATIONS. 

I made inquiries here, as also at Salerno, amongst the 
fishermen and coasting sailors, as to whether any of them 
had felt the shock at sea, but could gain no intelligence of 
any such observer. 

In the Ravina della Molini, behind the town of Amalfi, 
I observed some beds of ancient tufa deposited upon the 
precipitous sides of limestone at a considerable height 
above the present sea level. 

Along the road between Amalfi and Salerno there are 
proofs of an elevation bodily of the land of from 300 to 
400 feet since the formation and forcing up into a mountain 
range, of the great ridge of limestone that forms the peninsula. 
1st. Beach gravel in wavy layers, quite similar to that on 
the existing shore, is found 300 feet above it at Punta 
d'Erchia. 2nd. Between that and Amalfi, in the limestone, 
the beds of which have a north and south strike, and dip 
slightly to the west, there are caves, the upper portions of 
the jaws and arches of which, some 70 or 80 feet above the 
existing beach, present the rounded and water-worn aspect, 
of long-continued action of the sea. Objects, such as the 
porphyry font at Amalfi, alleged to have been excavated 
from beneath the beach — ruins now existing below the 
sea level here and there, go for nothing, as along a line of 
coast so extremely precipitous as this, of shattered lime- 
stone, and so frequently shaken by earthquakes, whole 
cliffs, have doubtless frequently been shaken down, and 
plunged beneath the sea. The limestone all along, from 
the point of Capo del Tumulo, is metamorphic and 
altered, in its bedding and cleavage, and presents in many 
places, highly magnesian, and in some, trappeau characters. 
Near Majori, fine masses of dark-brown stalactite occur. 



LA CAVA— MONASTERY OF LA TRINITA. 231 

containing very large plates of calc spar. All this, with 
the scattered patches of tufa, on the south side of the 
peninsula, where they never could have come mb dio from 
Vesuvius, indicate that submarine volcanic action, was 
going on in these regions, before the bay of Naples was 
separated from that of Salerno at all, by the elevation of 
the great limestone ridge now between them. 

At Vietri, which I visited in a violent storm of rain and 
wiftd, I could find no evidences of wave direction worthy of 
notice. At La Cava, the first very obvious trace of the 
earthquake challenged notice, in a long range of diagonal 
timber braces, sustaining the S. W. side of a range of house 
fronts, which had been thrown so as to lean outwards, 
bringing with them, the square piers of the old Roman- 
looking arcades, over which the houses are built (Fig. 119). 
In the latter were measurable fissures, though small; 
in the Casa Gommunale, and in the side and back walls, 
of some of the strange shadowy open fronted shops, 
that seem so identical with those of Pompeii, were a few 
others. From the whole I obtained three indications of 
wave-path — 15-30 E. of N.; S. to N.; 17 W. of N.— 
and also some indications of an orthogonal shock, W. to E. 
At the Benedictine monastery of La Trinita, a few miles from 
La Cava, I expected to have found much evidence of 
injury. It lies, in the gorge of a deep and sinuous moun- 
tain valley, of metamorphic limestone, hard and shattery, 
but with much diluvial covering in many places. 

The buildings, sound and well constructed, of rubble 
ashlar chiefly, have generally escaped. There are, 
however, in two diflferent places in its southern cor- 
ridors, and near the great south corridor window. 



232 SHOCK AT SALERNO. 

fissures of considerable length, and open at widest 
0*4 inch. They indicate a wave-path from the south- 
ward, and in direction 16° 15' W. of N., and also one 
105° 30' W. of N. or orthogonal. They felt the two shocks 
of 16th December severely at the monastery. Padre Mop- 
caldi, the Archivario, was not conscious of any noise at- 
tending either of the shocks, nor had any one else in the 
monastery remarked any. 

The forms of the small mountain valleys in this thickly 
inhabited region, are singularly winding and capricious 
(Fig. 120). A shock in whatever general directi(m 
acting here upon the houses and towers, perched on decli- 
vities, now rocky, now diluvial, and scattered here and 
there and facing every point of the compass, must produce 
efiPects in the highest degree complicated, or even unac- 
countable. I therefore resolved, in the first instance at 
least, to waste no time by further observation within it. 

Salerno, though an ancient city, is generally well built: 
it lies low, along the shore of a pebbly beach, and appa- 
rently on pretty deep beds of loose material, and the land 
behind it, rises gi-adually into mountain slopes, and reced^^ 
into sinuous transverse valleys on limestone. 

It has not suffered much, but there are abundance of lar^5' 
measurable fissures. I had a lengthy conversation wi 
the Intendente of the province. Signer Ajosso (who was co 
fined to bed and unable to go round the city with me^ > 
He stated that the shock was not sufficient to throw do^^^- 
furniture, or observably displace it, but that he saw it jer*^ 
the water out of a large earthen jug, which he pointed c^' 
in his bedroom, about 5 inches diameter of mouth, an*^ 
which had been full, within 2 inches. 



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THE INTENDENZIA— CATHEDRAL. 233 

Some china vases and table ornaments of common 
form, in his rooms were thrown upon the floor. Some of 
his oflBcials lost their footing and fell, during the second 
shock. He heard no noise with either shock, nor has he 
heard it stated that there was any sound heard by any one 
at Salerno. He furnished me with a copy of the official 
list of the houses destroyed, persons killed and wounded, 
&c., in the several Communes of his province, and letters 
to the Sotto Intendenti in the various parts thereof, and a 
general authority, under his sign manual, to call upon the 
Gruardia d'Urbani and Gendarmerie anywhere, if neces- 
sary to aid in my examinations.* 

The walls of the Intendenzia are rather heavQy fissured, 
especially through the window and door opes of the great 
stone staircase. The fissures in walls running E. and W., 
lean 10° to 13° from the vertical to the eastward : some are 
open 0'5 inch in 12 feet of length, and props and braces 
have been necessary. 

The building is ordinal, and from three of the best 
fissures, I derive a wave direction, 53° W. of N. 

The cathedral, a grand old structure, rich with the 
spoils of Psestum, brought by Roberto Gruiscardi, and of 
sound masonry, has its axial line (as I find is not un- 
common in these very old Italian churches) not quite 
E. and W. The axis is 23° W. of N. There were 
two formidable fissures, one in the apse at the N. E. side, 

* The iDtendente is very much the representative of the ancient 
Roman Propraetor. He possesses enormous executive power, often 
^ossly abused under the old regime. The civil, military, and eccle- 
siastical authorities are all more or less subject to his individual 



THE TBIBUNALE. 



at a, Fig. 121, the other at b, in the western transepts 
both not &r from vertical, and right down throngh 
wladow and door opes to the gronnd level, 
^.^y, from the roof. These were originated, the 

f ] Sacristan informed me, by small thread-hke 

U- / cracks (JUone) in 1851, but were widened 
' ' and lengthened now, in December 1857. 
a is now about 0*76 inch open near the 
top, and the roof of the apse has been suf- 
ficiently injured to require struts betwixt 
ceiling and floor. The dislocation of the 
roof here, indicates a certain amount of emei^nce in the 
wave-path (bat the fissures do not indicate any distinctly), 
10° or 12° at most. 

The direction I derive from them is 34° 30' W. of N. 
There are upon various points of the cathedral and attached 
buildings many slender iron crosses, the iron flat bars of 
al)out li inch % | inch thick, as in Fig. 122, none of 
which present any signs of having 
been bent or twisted. They were 
all confined, however, by small 
diagonal stays of round iron, about 
^ inch diameter. In the noble 
old cloister court, a long stone, 
part of the shaft of au old column 
that bad leaned against a wall 
running nearly N. and S., was 
overthrown, and indicated a wave- 
*'''''■ *^-- path of about 60° W. of N. 

Fissures, at the Tribunalc, gave a wave-path U7° W. of N. 
These fissures also aEfordcd pretty decisive evidence of the 




THE PLAIN TOWARDS P^STXJM. 235 

co-existence here of an orthogonal shock, or one from 
W. to E., but of very minor intensity, as was already 
noticed at Amalfi, Atrani, and La Cava. 

Several other churches that I entered showed no sign of 
injury. I was informed that the church of Saldina with its 
Campanile, not far from Salerno to the northward, had been 
seriously dislocated, more than any at Salerno. Time 
would not admit my diverging to it. 

Throughout the whole vast plain, from Salerno to 
Paestum, no visible sign of the earthquake can be found. 
It was felt however, sharply and with alarm, all over it, 
and the people very generally say it came from the eastward, 
in so far as their very loose expression "levante ver, 
ponente," may mean so. 

The outstretched plain between the mountains and the sea, 
is not perfectly level ; it slopes very gently seaward, and 
consists of a great depth of diluvial and transported material, 
all small where visible. At Paestum, and for a considerable 
distance round it, the fawn-coloured aqueous tufa, of calca- 
reous matter filled with the impressions of recent plants of 
a paludal character — great arundos, alder leaves and 
twigs, &c. — is found horizontally, everywhere at from 
6 to 1 2 feet beneath the surface, and no doubt overlies the 
limestone that supports the whole plain. 

Of this tufa, the majestic, solitary, and awe-inspiring 
Doric temples were built, with the town walls of huge 
ashlar all laid dry, that alone remain of what was once a 
populous city. Upon the dreary winter afternoon, on 
which I examined its ruins, no sign of life enlivened the 
desolate plain, but a flock of screaming green plover ; no 
sound was heard but the wind that sighed through the 



236 SEDIMENTS OF THE SALABIS. 

sedges and the distant and dismal howl oi some goatherd's 
dog. 

The fonnation of this tnfa seems to indicate the npheaval of 
the great plain at a recent geological period.. The lime has 
no doubt come, from the ground-np, and dissolved limestone, 
of the cretaceous formations, that constitute the lower 
mountain range, between the great mountain masses, of 
Apennine limestone and the sea. The latter occasionally 
comes forward in grand developments as at the Tusciano 
(Fig. 123), where the ranges under Monte Polveracchio 
show beds of vast extent and thickness, with a nearly 
horizontal strike parallel with the coast, and a noble 
sweeping curve, dipping steeply inland (about 30"^ or 
towards the N.N.E. Far beyond are high and jagged 
peaks, and a lofty sierra, thinly covered with a hoary head 
of snow, bounds the horizon, and glitters against the cold 
grey sky. Some twelve miles further south, the Salaris 
crosses the plain in a deep channel with heavy slob banks 
in the diluvium, about 270 feet wide, and with a rapid 
current, and turbid mud-stained water, of about 20 feet in 
depth. It drains a large area, in a course of more than a 
hundred miles, and the quantity of calcareous matter, both 
in solution by carbonic acid, and in suspension as mud, that 
it constantly brings into the sea, must be even now pro- 
ducing very sensible effects upon the coast, the dissolved 
lime forming the cement^ that rapidly agglomerates and 
hardens the calcareous mud into stone. This process seems 
also to be that, upon which the formation of the calcareous 
breccias found in such vast masses in the Apennines, has 
depended. 

Looking eastward towards, the valley through which the 



CAPACCIO— PiESTUM TEMPLES. 237 

Salaris debouches upon the plain, between Eboli on the 
north, and the Bosco di Persano, the synclinal beds of lime- 
stone are developed upon the grandest scale (Fig. 124): from 
a to 6 is probably not less than twenty miles, and the same 
beds can be traced by the telescope at either side. Above and 
between these the upper limestone, of the collines, seems to 
lie unconfonnably. Upon one of the most prominent of 
these towards the south are perched, Capaccio Nuovo and 
Capaccio Vetico, with the great adjacent monastery ; in all 
which, I was informed, the earthquake had been severely 
felt, but no considerable damage done. The general aspect 
of these branches of the Apennines, as I look back and 
into their recesses, is one of extreme confusion and dislo- 
cation, produced by long-continued and reiterated elevatory 
action of the most violent character, of which no just idea 
is given, by the surface configuration even of the largest 
maps, such as those of Bachler D'Albe and Zannoni ; and 
such as it would require years of labour from the field 
geologist to analyse and describe. 

At Psestum I examined the ruins of the temples with 
care, for evidences of the shock, but they presented not the 
smallest indication of dislocation. Formed, as they are, of 
extremely massive blocks, laid without cement, and with 
all the top weight due to Greek Doric architecture, few 
buildings could be by form and structure more amenable 
to "promptings from beneath." A careful examination, 
however, led me to conclude that since their foundation, 
they had suffered nothing by earthquake, not even to the 
opening of a joint — a sufficient disproof of the common 
tradition, that Peestum was deserted and reduced to ruin, 
by reason of the earthquakes that desolated the plain. 



238 DIRECTION OP SHOCK HERB 

So hr from the truth is this, that Capaccio, up in the 
mountain to which the Paestians are said to have migrated 
from the plain, has been repeatedly dislocated, and, appa- 
rently, the ruin of the whole town produced the founding 
of Capaccio Nuovo ; the other and older being now nearly 
without inhabitants. 

In fact, from whatever centre earthquake movement ori- 
ginates, along the mountain axis from Calabria northwards 
towards Melfi, &c., its spread is greatest and most rapid, 
in the lower and denser limestone of the higher central chain, 
and here, at the western seaboard plain, is almost limited 
by the line of outlying cretaceous coUines ; the blow trans- 
mitted from which through ten or fifteen miles of soft 
porous tufa and loose material, principally deep calcareous 
clays, is completely buffed and lost, before it reaches 
Psestum and the shore. 

The family and servants of the landowner at Paestum, 
a great number of whom I found collected at the Casone, 
were unanimous that the shock of 16th December was 
simply " oscillatorio," and in direction "levante ovvero 
ponente," that they had felt but one shock, and had heard 
no noise. On causing some of them to point out separately 
for me, from the balcony by the hand, the direction '^^ 
which they deemed the shock traversed, and comparing 
it with the azimuth compass, I found it was very nearly 
E. and W. 

They said the dogs (of which they keep a great number 
of large formidable animals to take care of the buffaloes, &c.)» 
had barked violently and universally, for a good while before 
they felt the shock. Most of the people were in bed. Tbey 
could give no information as to the time beyond crude 



AT AGROPOLL 239 

guesses. The shock had been felt, they said, far worse at 
Agropoli and below it, than with them ; naturally so, for 
the limestone mountains jut out into bold promontories and 
come down to the sea at or near that town. At Capaccio 
Nuovo they said the shock had also been felt from E. to 
W., and more from the north, than with them at Psestum. 



CHAPTER V. 

ENTRANCE TO THE MOUNTAINS AND TO THE REGION OF 

RUIN — EBOLI — CASTELLUCCIO. 



The buildings of the Locanda di Vozzi, at Eboli, are 
those of an old, suppressed monastery of the Rifonnati, of 
great size, nearly square, and not far from cardinal, but two 
stories above ground, and extremely well circumstanced for 
observation. 

The front with the campanile (Photog. No. 124, bis) along 
the main road bears 23° W. of N. Its internal construction, 
generally, consists (block plan. Fig. 127) of a central 
interior court, surrounded by a double range of rooms 
with a corridor between, running right round the whole 
building. Two of the corridors, and a few of the largest 
apartments, are vaulted with brick or rubble arching ; the 
others, as well as nearly all the rooms, are timber floored. 
The rooms are chiefly small, having been formerly monks' 
cells, and separated chiefly by walls of one brick thick. 
The external walls generally are 22 inches thick, of stone. 
There are four huge external buttresses on the south side, 
up to the level of the iirst floor, built after the shock of 
1851, which shook the building a good deal. There is a 
stubbed old cylindrical tower at the N. B. quoin, and a 
small external terrace and building at the S. E. one. The 



LOCANDA DI VOZZI. 



I. and S. corridors are vaulted, the E. and W. oaes timber 
cored. .j>- 




Fif. 1-J7. 

SKKTCn OF I.OCAMDA DI VoZZI AT EUOU 

{fonaerty a Mtaiadcry of Riformati) . 
k.-«iinuUe. C. C, OIU or duioiben. 1, 1. 8u>ik butlnsiM. K. Kllcl»n— ismioDn roonn, psdnnie. tc. 
^>, Fon eonrt. P, Tultol corndon. V, VauIiFd cbmnlxn. T, Tower. S, Souu open Umm, 
/ I thill muknl m wall GiMura. 

^he whole buildiDg is fissured in almost every part, 
^ yet not uninhabitable, all the fissures being narrow, 
3 but moderately inclined, and its peculiar cancellated 
Victure has, by the help of the mid lines of corridors, 
S>t the roofing uninjured nearly. 
Vol. I. B 



242 WAVE-PATH FROM FISSURES. 

The fissures that are most instractive, are those in the 
external quoins, those on the soffits of the arching, and 
at the junction of the cross walls between the rooms {(x 
cells) and the external walls. 

The fissures resulting from the shock of December last 
are readily distinguishable from those of 1851. The 
walls have been all limewashed more than once, in the 
interval of time between, so that the former fissures are 
filled and obscured, those of December last, new, clean, and 
empty. The largest fissures are open 0*3 to 0*5 inch in 
10 feet. They are wider, larger, and more numerous on 
the S. and E. wings. The width of similarly circumstanced 
fissures on the E. and S. wings are on the average of 
eleven pairs as 7 : 6'5. The angle {6) made by the path 
of the wave with the east flank wall, therefore, was 

6-5 
Tan = — = -93 nearly, 

or = 43°, but the building is ordinal 23° W. of N., adding 
this, we have the azimuth of the wave-path at Eboli 
= 43° + 23° = 66° W. of N. 

None of the photographs (Figs. 124, 125, 126, Coll. Boy. 
Soc), were taken sufficiently near, unfortunately, to show 
with distinctness any external fissures in this building, nor 
to show the S. W. angle at all. Referring to the block plan 
and elevation (Fig. 127), however, some large fissures in the 
external walls of the projecting buildings over the ter- 
race, and, generally, in that portion of the structure, give an 
angle of slope with the vertical = 15° to 16°, and allowing 
for the change due to the ordinal of the building, indicate an 
angle of emergence for the wave-path ^ = 18° from the E. 

The church was the only other building I could find at 



CHURCH AT EBOLI. 243 

Eboli giving distinct indications. It is almost cardinal, and 
shows some pretty extensive sloping fissures in the walls 
of the apse, behind the altar, and in the N. wall of the 
nave, these being respectively nearly orthogonal. The apse 
fissures are comparatively insignificant, and fi-om the form 
of the walls difficult to compare with those of the nave. 
The general deduction as to wave-path, however, coincides 
pretty nearly with that from the Locanda, being E. to W. 
and some degrees to the N. of W. The slope of the 
fissures in the N. wall of the nave gives for the angle 
of emergence e = 21° 30' from E. 

The people generally at Eboli, and more particularly 
those of the family of the Padrone at the Locanda, state, 
that they experienced both shocks from E. to W., and that 
there was a considerable amount of vertical movement 
(sussultatorio). 

A very intelligent man living at La Sala, but who was 
at Eboli on the night of the shock, whom I met at the 
Locanda (but whose name, I regret to find, I did not note), 
agreed with their notions, but thought he had also felt a 
sharp jerking shock from the N. or E. of N. directly after 
both the first and second principal shocks. If this be so, 
it would probably be accounted for, as a reflected wave 
from the high hills that overhang Eboli to the N. and N.E. 
No one heard any noise attending the earthquake. 

The level of the ground on which the Locanda stands, as 
given by reduced barometer observation, is 326*8 feet above 
the sea. Barom. reads 29° 72', thermo. 50° Fah. at 9*^ 25", 
Nap. m. t. (26th February). 

At the Locanda of Eboli, I had the good luck to fall in 
with Signor Palmieri, the engineer of the corps of Ponti 
e Strade, to whom I had a letter from the Intendentc 

R 2 



244 LIMESTONE BRECCIA. 

Ajossa, and during the evening spent with him I obtained 
a great deal of useful local and other information, as to 
matters of fact from him. 

He gave me circumstances I deemed conclusive, that the 
wave-path had been from N. to S. at Lago Negro and at 
Sapri, and at Laurino from the S.W. to N. E. I fell in 
again with Signer Palmieri near Polla, whence he was 
returning, and was indebted to him for first calling my 
attention to the instructive facts developed at the Palazzo 
Palmieri there, which he had just been examining. 

About four miles from Eboli I crossed the Salaris by a 
grand old irregular bridge of one very large semicircular 
arch and several minor ones, and here first observed masses 
of the limestone pebble breccia, of the Apennine formation 
(the bridge is built of it), which, from this eastward, 
appears to overlie the limestone and underlie the deep ' 
diluvial clays and gravels of the valley bottom. The 
pebbles hereabouts arc usually from two to four inches 
diameter, much water-worn and rounded, of a brown-grey 
and fawn-coloured argillo-calcareous rock, with a good 
many occasional pebbles of a tea-green, cherty, meta- 
morphic slate, so hard as almost to resemble Jade. The 
cementing material is calcareous, and the interstices of the 
pebbles are filled with fine gravel and calcareous sand. It 
is a coarse but good building stone, and indurates much on 
exposure. In situ, this breccia here is stratitied in gi-eat 
coarsely-defined and irregular beds, which generally ap- 
proach the level in strike, though much tilted trans- 
versely to the line of valley. 

At the fork of a small stream, the Merdarolo (or Pag- 
liardo according to some of the peasants), where it joins 
the Salaris on the left bank, beds of limestone tilted 



PIANO OF SAVANUOLA— ALBURNO. 245 

almost vertically appear with a lithological character al- 
most identical with our English lias limestone. They are 
unconformable with the enormous pile of limestone beds, 
nearly horizontal in strike along the valley, but dipping 
sharply to the south, which form the huge, shattered, and 
decussate precipices, rising to the summits of La Scorza or 
Monte Alburno. These summits shut in the Piano of 
^vanuola, a singular irregularly oval-shaped, and moun- 
tainous table-land, of more than twenty square miles in 
surface, and, beyond it, I get occasional glimpses of still 
higher ridges and peaks. The range of Alburno must rise 
to at least 3,000 feet above the plain between Eboli and 
the sea, and is now (12th February) covered with snow, 
for about half the depth down from the top, wherever it 
can lodge upon its abrupt and precipitous flank. 

For about the lowermost third in height on both sides, 
the valley is covered with smoothed, rounded, and sloping 
masses of diluvial clays and gravels, with huge angular 
blocks and boulders dislodged from above scattered here 
and there. 

Noble natural oak forest, clothes much of this down 
nearly to the valley bottom, as in the days when Virgil 
wrote his third Gteorgic : — 

" Asper acerba sonans ; quo tota cxterrita syl-vis 
DifFugiunt armenta, furit mugitibus aether 
Concusstis Bjlvceque et sicca ripa Tanagri.*' 

Through these and below them, the rain has cut into these 
clays in a surprising manner, and in many planes they 
seem as if subsiding bodily, from off the steep sides of 
the hills, and melting into the muddy flood of the Salaris, 
which, a few miles further eastward, unites its current 
with that of the Rio Negro or Tanagro, falling in upon its 



246 



THK FIRST PROSTRATE WALLS. 



left bank, between the towns of Contursi on the north 
and Postiglione on the south, right under which are the 
ancient and the new post-houses of La Duchessa. 

Here the first walls actually prostrated by the earth- 
quake become visible (going eastward). The old post- 
house is now a roofless ruin, of walls standing two stories 
(without floors) or about 30 feet in height, about 250 feet 
long by 45 feet wide, built of rubble limestone, wi^ 
ashlar quoins. None of the stones of the walls exceed aboat 
6 ins. X 12 X 12, or 18 at most; poor masonry, but DOt 
iU suited to seismometry. 

The place was damaged by the earthquake of 1 783, and 
rendered uninhabitable by that of 1851. Its general lengtii 
bears 135° E. of N. The fractures and fissures produced in 
December are clear and distinct from the old ones. In the 
sketch (Fig. 128), the portions coloured black indicate the 




Hood 



to AaletttL, 



TSkw RbI 'HiaoBS, 



Fig. 128. 



walls partly or wholly fallen ; and the places of the prin- 
cipal measurable fissures are marked //, &c. The fissures 
of the S. E. end when reduced, give 76° W. of N. for the 
wave-path, those at the opposite end 73° W. of N. the 



INDICATIONS CONFLICT WITH THOSE AT NAPLES. 247 

mean = 74° 30^ W. of N. Those at the former end are 
pretty evenly and uniformly sloped, and at an angle 
with the vertical = 24°, giving that for the angle of 
emergence of the wave-path. Some of the fissures, how- 
ever, gave an angle of emergence as steep as 32° or 33°. 

This indication puzzled me much. The N. and S. direc- 
tion of wave-path at Naples, and on the south side of 
the bay, led me to expect that I should find the focus of 
the shock had been somewhere at sea, under the Gulf of 
Salerno, or that of Polycastro ; and this was supported by 
continuing to find that the wave-path from Salerno and 
southwards was W. and E. more or less. I was not 
shaken from this hypothesis, by finding that no traces of 
the incoming of a roller or great sea wave had been 
observed anywhere along the coast from Salerno down- 
wards ; but the finding these fissures at Duchessa, leaning 
oflF towards the south and east, seemed irreconcileable with 
any possible position of focus that could account for the 
observed wave-path at Naples, inasmuch as it could alone 
be the result of a focus to the eastward of Duchessa, and 
therefore far away from intersecting any line drawn nearly 
north and south through Naples. I summoned my faith 
in induction to my aid, however, and trusted to the witness 
of further facts to solve the mystery. 

The postmaster here, had heard a sound along with 
the shock: he thought it came rather before the actual 
oscillation, which was undulatory also. He was standing 
up, in the room in which he slept, and described the sound 
at or preceding the first shock, " Not loud but a quick 
sort of deep hoarse buzz " — " Roco ronzio profondo vivace, 
ma piccolo." He could not tell whether there was any 
sound with the second shock or not — " he thought there pro- 



248 SOUNDS HEARD HERE. 

bably was — but they were all in great alarm." One or two 
considerable fissures had been produced in the new post- 
house. I took observation of the sun here to determine 
the magnetic declination, and give the result as worked 
out, but am satisfied I must have committed some gross 
error in the observation or note of it. 

Duchessa, Lat. 40^ 34' N., Long. 15° 11' E. (Feb. 13) 
Hour angle at time of observation = 24° 6' 48"" 15, 
Sun's azimuth computed . . = 27° 42' west. 
Sun's bearing by compass . . = 20° 0' east. (?) 



Magnetic declination . . = 47° 42' east. 

There is no ground for assuming any serious local disr 
turbance of declination hei^e. 

From a little beyond Duchessa, off to the eastward, and 
rather to the south, Sisignano is seen perched upon a spur 
of Monte Alburiio, that runs in a S. E. and N.W. direction 
aiagonally across the main valley and down to the Tanagro. 
The road continues to rise rapidly, ascending over the 
shoulder of this, at the little village of Lupino, and to the 
south or right hand. The vast pile of limestone beds of 
the Alburno is seen stretchin"^ away with nearly horizontal 
strike, parallel to the general line of the great valley, and 
dipping sharply to the west and south-west, at probably 45°. 
The transverse ridge is too much covered to enable me to 
prove, what I conjecture from its outlines, that it consists 
mainly of the breccia limestone, uuconformably laid on the 
beds of Alburno. 

After about six miles, the highest point of the transverse 
ridge is reached, near Lupino, and I determined its height 
by barometer, which reads, at 1-32 Nap. mean time, 28-78 



LUPINO— SISIGNANO. 249 

inches. Thermo. 52° Fahr. (13th Feb.). This reduced, 
gives 1441*3 for the altitude. (See Appendix for particulars 
of all barotn. measurements and reductions, %c.) The 
transverse ridge here, is a complete dividing barrier, upon the 
south side of the Tanagro, between the great valley of the 
united streams of the Salaris and Tanagro, and that of the 
latter river, into which I begin now to descend again rapidly, 
to within perhaps 400 feet above the bed of the river. 

At Lupino, almost no damage was done. The few houses 
are low, well built, and not very old. The postmaster 
here was rather uncommunicative. " They had been severely 
shaken and much alarmed, but knew of no damage done at 
Lupino. I should find plenty six or seven miles further 
eastward." I can see with the telescope the old chateau on the 
highest part of Sisignano, overthrown and in ruins, and a 
good deal of damage in the place itself. Gualdo, with 
Terra Nuova, are above me on the south, but neither have 
suflFered very much. About two miles further on I pass 
the Taberna of Urma, a small post-house, with a new and 
yet unroofed Capella close to it, which had just been built, 
and the mortar of its limestone rubble yet fresh and soft. 
It was a building of one story, about 30 feet E. and 
W. by 24 feet N. and S., and the walls about 17 feet high. 
These are fissured, at three out of the four quoins in such 
a manner, that the ends tend to come out. The fissures 
are widest at the east end. The axial line is exactly 
cardinal by my prismatic compass, and the fissures give a 
wave-path of 81° 30' west of north. The stones are large 
in proportion to the size of the building, and I can get no 
indication reliably as to emergence. 

Numbers of fissured buildings now begin to present 
themselves, all indicating as I pass them a general east and 



260 STONES DISLODGED IN VALLONE PETROSO. 

west direction of wave-path. A little further on, after 
passing a torrent that falls into the Tanagro from the south, 
I look up an extremely steep lateral valley — II Vallone 
Petroso — in which many loose surfece blocks of limestone, 
show themselves to have been shaken from their positions 
and rolled over : from the road at this point there cannot be 
less than 3,500 feet vertical, of calcareous beds above me. 
The geological evidences of violent dislocation and elevation 
at all sides in the mountain formation are strikingly grand. 

At the 58th milestone from Naples on the military road I 
am close under Castelluccio, a strange, immured, and gloomy- 
looking mediaeval town, perched on the very crest of a solid, 
rounded, lumpy mass of limestone, showing little or no signs 
of distinct bedding, and with its sides so steep, that trains of 
loose stones lie in huge furrows, straight up and down its 
flanks here and there. The Tanagro flows at the opposite 
side or round to the north of this hill, while its tributary 
from the Yallone Petroso winds round the foot of the enor- 
mous rock, (see Photog. No. 13, Part I.,) to join the former 
to the N. E. The town and its eminence thus stand upon 
a sort of peninsula, rising more gradually from the main 
valley upon the westward, and having the longer axis of 
the rocky mass nearly in an E. and W. direction. 

Although close enough to see the joints of the masonry 
in its walls, through the keen clear air, with the naked 
eye, I found it would require four hours' time to climb up 
to the town ; and learning that it had sustained but very 
little damage, I did not attempt to lose time in the ascent, 
but scanned it narrowly with the telescope in a fine light. 
Not a single fissure was visible in the N. W. or E. sides 
of its external walls, which, although they look like those 
of a large fortified mediaeval town, are in reality only the 



CASTELLUCCIO. 



rear walls of the houses turned outwards, and built closely 
together, and upon the very edge of the steepest escape- 
ments of the rock. Such are the characteristics of many 
of these most interesting old towns. 

But I can see that the top of the cupola of the highest 
campanile or tower in the place, probably that of the 
church, has been broken oET short and is gone, obviously 
by the direction of the fracture, by a force from the 
eastward and a little south, or about 70° W. of N. by 
estimation (c, Fig. 129), being, as figured, at the east end 
of the cupola, which was an hexagonal, Saracenic sort of 
small dome, of limestone, obviously modem. 

As I move round the base of the rock, I can see thus 
much reason for its comparative security, that the mass of 
solid limestone upon which it rests, presents its long way 
to the length of the valley, and lies nearly B. and W., 




Fig. 130. 

witb its steep end towards the east, and buttressed away to 
the westward by a longer slope, as in the section E (Fig. 130) 
taken in a line with a b. 



252 CHIESA DTNCORONATA. 

Quite beneath Gastelluccio, between the road and the 
torrent, that rushes to the Tanagro round its base, and some 
100 feet below the road level, is a solitary church, La 
Chiesa d'Incoronata. It stands upon a low lying spur of 
deep diluvial clay and gravel, upon nearly the edge, 
that scarps sharply down, covered with natural oak 
and hazel, to the torrent of the Petrosa, and is greatly 
damaged; the whole of the east end having fallen out, 
carrying much of the roof with it. Upon descending below 
it, through the woods, I find that the deep diluvium above 
rests upon argillaceous beds, which are nearly vertical, 
and strike across the valley in a N. W. and S. E. direction, 
and so are almost parallel with the ridge of Sisignano 
and Lupino, already passed, and which appear to be wholly 
unconformable to the limestone breccia of Monte Carpineto ; 
the subordinate mountain, to the continuation of the N. 
scarp of Monte Alburno, and which lies S. and S. E. of 
Gastelluccio. 

This church is a poor building, the walls about 15 feet 
high and 2| feet in thickness, of coarse limestone rubble, 
covered with a heavy tiled roof upon gross, ill-framed 
timber. The north wall had, in part, long leaned outwards 
(as I was informed by the priest), and a portion had fallen 
towards the north ; but all the remainder of the east end 
had fallen outwards, or in a general direction of the line 
a to ft (Fig. 131), and a much larger portion of the roof, 
as indicated by the irregular line c c, had come down and 
fallen within the walls. In both the north and south walls 
were some fissures ///, which, together with the general 
direction in which the mass of dislodged material had been 
thrown, indicated a wave-path of from 80"" 30' W. of N. 
to nearly due W. and E. The mode in which the roof 



MONTE CARPINETO. 



253 



had come down, seemed to indicate a considerable amount 
of emergence in the wave-path, from the eastward, but 




Fig. 131. 

how much, neither it, nor the direction of the fissures, in 
the coarse rubble, and through the heads of the windows, 
would indicate. 

Monte Carpineto is part of a subordinate range, that 
stretches in a N. E. and S. W. direction, as far as Salvitella, 
northwards, almost at right angles to the great north scarp 
of Monte Alburno ; the Tanagro piercing through it nearly 
at right angles, about half way between Petina, on the 
south, and Salvitella ; and the much larger stream which 
comes away from far north of Muro and Bella, in the lofty 
recesses of Monte Croce, and joins into the Tanagro at 
Castelluccio, and properly should be called Tanagro, taking 
the name of the Bianco. The descent is extremely rapid 
from about the 59th milestone, or half a mile beyond ; and 
BS the new valley begins to open, I catch the first glimpses 
of Auletta, and even at this distance perceive the terrible 
evidences of the overthrow it has sustained. 

Monte Carpineto once passed, the general direction of the 
main valley changes, and I descend into a deep and nearly 



254 FORM OF THE YALLET HERE. 

closed-in hollow, between smaller lateral valleys nmning 
nearly north and soath, and opening in common npon the 
course of the Tanagro, in which Auletta and Pertosa, each 
perched upon a separate spur or colline, and each in the 
mouth of a separate but closely adjacent valley, are 
situated. 

Upon the south-east, this hollow is completely barred 
and closed in, by the mountain of Taliata at the west, and 
the ridges of Monte Sarconi on the east, which abut upon 
each other, with nothing intervening but the tremendous 
cleft, through which one portion of the Tanagro forces its 
way from the north end of the Piano di Diano; while 
another portion of it, disappearing there, finds its way by a 
subterraneous channel, nearly parallel with that siJb dio^ 
and both meet again at Pertosa ; the subterraneous waters 
discharging from the mouth of St. Michaers Cave, at a 
level of about 200 feet above the open bed of the river, 
opposite Pertosa, and turning the wheels of some old 
Catalan iron forges, before falling into it. 

Although from this point the Tanagro pursues the same 
direction, as lower down, nearly from E. S. E. to W.N.W., 
the whole character of the valley itself has changed since 
passing Castelluccio, it is no longer a great E. and W. valley, 
but an irregular deep boUow, produced by the abutting and 
inosculation, of several secondary mountain ranges and 
valleys, running more or less N. and S., and gradually 
shutting up the hollow, until Auletta and Pertosa seem 
enclosed within it. 



CHAPTER VI. 

ENTRANCE WITHIN THE MEIZ0SEI8MAL AREA — AULETTA 

— GREAT EARTH FISSURES. 



I HAD no sooner passed into this hollow, than it became 
evident, that all at once, I had got within the radius of 
formidable earthquake violence : on every side ruined 
and prostrate buildings presented themselves. Descending 
towards Auletta, I can see Buccino greatly elevated, 
and some six miles to the north : many of the people here 
call it BngUle, pronounced like French, without the final 
voweL This corrupt pronunciation of names is frequent, 
and renders recognition by maps often difficult; the 
same name is often pronounced half a dozen different 
ways by as many persons — ^an existing example of that 
jargon of living tongues, betwixt closely adjacent places, 
of which Sismondi gives so vivid a picture in those very 
regions, in his * History of the Literature of the South of 
Europe in the Middle Ages.' 

At half a mile in a right line from Auletta, I pass a 
mined house, of one story, of about twelve feet in height, 
and about twenty feet square in clear of walls, which are 
two feet thick, pretty well built, and not above ten or 
fifteen years of age. This and a much larger building, 
a sort of farmstead, at the opposite side of the road, with 



HOUSE NEAB AULETTA. 



a great spread of gable, and iront parallel to this little 
house, present evidences of great violence here, and ex- 
tremely steep emei^nce of the wave. The house (Fig. 
132) is fissured from wall plate and ground, in the north 




and south walls, near the quoins, and over the entrance 
door, the lintel of which, a single slab of limestone of about 
12 in. by 22 in. wide, is fractured right through by the 
rocking of the wall at either side of it The roof is all 
fallen in, except one purlin, which is stilt in situ, and 
proves, on examining its ends in the gable walls, that the 
east gable, and the roof along with it, all came to the 
eastward, at the first movement of shock, drawing the 
purlins from their sockets in the west gable; some were 
drawn quite out, and the roof at once fell in ; others 
returned by the back stroke of the wave, and drove the 
ends of the remaining purlins, back again into their sockets 
like battering rams, throwing out portions and dislocating 
the west gable. The north-west quoin has had a long wedge- 
shaped mass projected right outwards, showing a very 
steep angle of emergence. The dislocations generally, here 
and at the opposite side of the road, give evidence of a 
wave-path from E. to W., and an angle of emergence of 
upwards of 45^ with the horizon. T did not measure any 




riiANSV£RS£ SECTION A '0 8, 



SITUATION, ETC., OP AULETTA. 257 

mgles, however. In this house a whole family were 
crushed beneath their humble roof : they had been asleep, 
ind, awakened by the first movement or by the noise, had 
tried to escape, but the broken lintel, had jammed the 
Dbdurate oaken door, just within which their bodies were 
Found collected, beneath the mass of tiles and timber. 

Auletta stood upon an elevated knoll, jutting with a 
3. E. direction from the E. slope of the mountain, of its own 
N. and S. valley, with the Tanagro sweeping past its base 
to the southward, and joined by a small torrent on the 
right bank from the Auletta valley. The bottom of the proper 
valley of the Tanagro here presents a broad level plateau 
of a mile or so across, upon which, at the river and beneath 
the base of the knoll, are some other houses, &c., with a 
poor and now half-ruined locanda, that also go by the name 
of Auletta. The town iteelf on the top, had about three 
thousand inhabitants, some fine large houses inhabited by 
oflScial persons, and a mass of poorly built ones, all of the 
nobbly limestone rubble. It is mediaeval, and was fortified 
in the middle of the sixteenth century, the castello alone 
now being the only visible fragment of this. 

Referring to the eye-sketch (Fig. 132), the spur or 
elongated knoll upon which it stands has a general direc- 
tion of N. 60° W. The N. E. side is extremely steep. 
From the highest point of the remains of the castello I 
found by the theodolite the general angle of the scarp to be 
41° from the vertical. The opposite, or S.W. side, slopes 
much more gently. The N.W. junction with the mountain 
range, is a little depressed below the summit at the town, 
and undulatory. The spur consists of coarse calcareous 
breccia, in heavy irregular beds, with a nearly N, and S. 

VOL. I. s 



258 HYPSOMETRIC ELEVATIONS. 

strike, and dipping 35° to the S. and S.W. These are visible 
here and there all over the steep scarp, and at several points 
in ascending from the locanda, along the road at the S.W. 
flank. The character of the rock, which is the average of 
most of the breccia hereabouts, is seen in Photog. No. 133 
(Coll. Roy. Soc.), taken from within forty or fifty feet of the 
rock ; the pebbles are from three to ten inches diameter, 
and extremely round. The steep scarp is almost bare rock, 
but that to the S.W. is covered to within one-third of the 
height, or less, from the top, with diluvial clay, and olives 
grow over the whole slope. The clay is perhaps thirty 
to fifty feet in thickness near the base, between the road 
up towards the town and the Tanagro, thinning off to 
nothing as we ascend. 

At the bed of the Tanagro, below the bridge that passes 
over the great military road, barom. reads 29*76 in., thermo. 
51° (13th February). At the locanda, which is on the level 
of the valley piano or bottom, (14th February,) barom. 
29 50 in., thermo. 52° ; and at the summit of the town on 
top (13th February), barom. 29*41 in., thermo. 48"". These 
reduced (see table. Appendix), give for the respective levels 
above the sea — 

Bed of the Tanagro 576*0 feet. 

Valley piano, or bottom 647*6 „ 

Summit of Auletta 889*5 „ 

The spur is therefore 242 feet nearly above the valley 
bottom. It can be scarcely half a mile in a right line 
across the base in a direction A to B of section, and 
perhaps two miles the long way, in its projection from the 
main slopes. 



MAGNETIC DECLINATION OBSERVATIONS. 259 

A knowledge of the magnetic declination, as aflfecting 
all my determinations, rendered frequent observations to 
ascertain its amount important; unfortunately, from the 
season of the year, and inclemency of the weather in these 
mountain regions, the observation of the sun or pole star 
was practicable but seldom. I therefore, in addition to 
such solar or stellar observations as were possible, took 
magnetic bearings, from many elevated known points, of 
others visible from them, and recognizable again upon the 
two great maps of the country, Zannoni's and Bachler 
D'Albe's, so that, by comparing the observed bearings 
with those of the maps, the declination might be checked. 
I took the following bearings at Auletta : — 

Villa Carusso bears from Auletta 7° W. of N. 

Contursi 43° 30' W. of N. 

Castelluccio 56° 3' W. of N. 

Petina 93° 0' W. of N. 

Caggiano 89° 0' E. of N. 

Pertosa 82° E. ofN. 

These give from 14° to 14°-50' declination W. 

On the 13th February I was able to see the sun's disc, 
though not perfectly clear, and take observations. At 
9h. Om. Greenwich time by chronometer, the centre of the 
sun's disc bears 24° E. by compass. Taking Auletta to be 
in lat. 40° 30' N., long. 15° 23' E. 

The hour angle at time of observation = 32° 25' 34"-50 

The sun s azimuth = 36° 20' East 

Ditto by compass . =24° 0' East 

Declination = 12° 20' West 

s2 



260 CONDITION OF AULETTA. 

This result may be in eiTor a degree or two, for the 
latitude and longitude are had from map measurement, 
and .the cloudy mist that hangs at this season all the 
forenoon, over the chill waters of the rivers in these 
mountain valleys, precludes good observation. The de- 
clination here is not, therefore, far from the same as at 
Naples. 

Auletta has suffered much from the shock, most so, at its 
highest portions, and upon the N. E. side of the summit, 
where the most substantial buildings stood, and upon the 
S. W., where were some of the poorest and worst. 

The general appearance of the locality is seen in Photog. 
No. 134 (Coll. Roy. Soc.) from the road sloping up to the 
town, and Photogs. Nos. 135 and 136 give two views nearly 
at right angles to each other, of some of the most instruc- 
tive buildings at the upper part of the town (No. 135), 
looking, about N.W. 

The propped wall, in both Photogs. is the same, and is 
square to the four parallel walls, which in No. 136 are 
observed all shorn off and thrown, from the western quoins. 
This is a good example of the parallelism of angle at which 
such fractures form in kirge masses. 

At the lower part of the town, and upon the slope towards 
the N.W. leading to it, the fractures all indicate a very 
steep emergence from the eastward — upwards of 45° ; but 
upon the summit, the buildings show a lower apparent 
angle of emergence, and greater dislocation. This obviously 
arises from the fact that, as the wave-path hereabouts was 
in some direction from E. to W., and therefore diagonallv 
transverse, to the narrow or thin direction of the spur, upon 
which the town stands ; the mass of the spur itself vibrated 



EFFECTS ON TOWNS PERCHED ON SUMMITS. 261 

with the blow as an elastic pendulum, so that its proper 
motion at top, which was quam prox. horizontal, was added 
to that of the emergent wave, thus reducing the direction 
to one of less emergence, and increasing the range and 
velocity of movement upon top. The great majority of the 
fractures at Auletta, indicate a wave-path E. and W. by 
compass ; those of the castello, which is prostrated to the 
level of the first story, and stands upon the very brink 
of the precipitous side, when reduced give one of 115° W. 
of N. ; but the buildings are not isolated, and the direction 
has been probably perturbed by this, and by longitudinal 
vibration in the mass of the spur on which it stands. On 
the whole, the wave-path here is E. and W. 

The effects, of the form, elevation above its base, sub- 
stance, and direction with respect to wave-path, of the 
collines or spurs, upon which so many of these towns are 
perched, in modifying the results of the shock upon them, 
are strikingly seen here, as well as at Castelluccio, which we 
have passed, and at the little village of Petina, which, from 
a point between this and Pertosa, I can descry with the 
telescope, perched high up, upon the south scarp of Monte 
Albumo, at least a thousand feet above me. It stands 
upon a level sort of short, stumpy, buttressed spur, jutting 
out from the steep mountain slope, which in form is like a 
piece of artificial earthwork, the little town standing upon 
the level platform on top, with a steep scarp in fi^ont of it, 
the mountain rising abruptly behind, and the scarp sloping 
in and getting lost in the mountain sides to the E. and W. of 
the town. The terrace upon which it stands, however, is not 
earth, but solid limestone— a projection, of the great hori- 
zontal strike of the beds, of the great scarp of Alburno, as 



in Fig. 137, which dip pretty sharply to the south, I 
flad upon inquiry here that Petina, which is just five 




Fig. 1S7. 



Italian miles S.W. of Anletta, and about six from Pertosa, 
has nevertheless suffered absolutely nothing, although these 
latter towns arc in great part prostrated. 

The immunity of Castelluccio from injury arose, as I 
before remarked, from the long dimension of its well-bnt- 
tressed kuoll being ojiposed to the line of s/tock, as well as 
to the barrier interposed between it and any shock coming 
from the eastward, by the mass of vertical breccia beds to 
the east of the town. 

Petina has owed its immunity, first to the peculiarly strong 
form of the terrace upon which it is perched to resist any 
vibration in the mass itself, secondly, to the feet that from 
where I stand at Anletta Bridge, there is about 1,000 feet of 
piled-up limestone beds between me and Petina, so that any 
shock cnicrgeut at a steep angle, here or further eastward, 
must have passed ui) transversely through all these succes- 
sive plates of varialjle hardness, and none in absolute con- 
tact with each other, and so the vis viva of the shock be 
enormously reduced before reaching the elevation of the 



• EARTH FISSURES AT AULETTA. 263 

village. This is probably also the reason why huge 
masses, of the towering and ruiniform crags, that form the 
highest summits of Monte Alburno, far above Petina, have 
not been brought also toppling down into the valley. As 
it is, however, I find, according to the information of the 
guard of gendarmes here stationed, that there have been 
some heavy falls of rock in the Vallone Petroso, and at 
other places along this end of the scarp of Alburno. 

At Auletta it was alleged to me by these gendarmes, 
who arrived there within a day or two after the shock, and 
whose statements were confirmed, by those of some dozens 
of the poor inhabitants, that large and long fissures had 
opened in the earth around the town, but that they had 
since all become closed again, and they doubted that they 
could now be seen. I gave much scrutiny to this, and having 
got the corporal of the guard to come with me, he pointed 
out the place where he had observed one of the largest of 
these fissures, to the north-west of the town, amongst olive 
grounds, and in deep clays (at F, Fig. 132). After some 
time I found myself unmistakeable traces of the fissure, in 
a continuous sort of little narrow trench, about 12 or 15 
inches wide, at the widest places on the surface, but 
generally not more than 8 inches wide, and of a blunt 
Y shape in cross section, with rounded edges, and not 
above 8 or 9 inches deep, as in Fig. 132. The whole interior 
surface between the lips was free from vegetation, which 
grew, in many places, close up to the edges, and corre- 
sponded on opposite ones. There was no denying the 
evidence of a recent fissure, filled up still more recently, by 
the slow sinking together of the sides, and by the washing 
in of earth by rain. I was enabled to trace it along the 



264 THEIR DESCRIPTION AND PROOFS OP 

surface, with but occasional breaks of continuity, where 
the rain had washed illuvium transversely and filled it, or 
where the ground had been tilled between the olives, for 
more than a quarter of a mile. I was informed by the same 
soldier (whose testimony I had thus proved trustworthy) 
that he had himself traced the fissure F for nearly two 
Italian miles in a west and south-west direction, which was 
one generally coinciding with the horizontal contour along 
the slope of the hill side- Returning back to whence we 
started, I found two divergent fissures (as figured), and 
traced one of these in a S.W. and S. direction for some 
h undreds of feet, down through the olive orchards parallel 
to the road up to Auletta. The one from A to >E; led me to 
try to follow it in a contour line, along the S.W. slope of the 
town, and without much difficulty I found it again, where 
the earth got deeper, and traced at several points, but not 
continuously (much matter having been washed across it 
on this steep slope), the fissure /. It was a similar little 
trench to the former, but as in Fig. (a, 132), one side of 
the V greatly higher than the other, smaller in size, and 
harder to trace than the preceding from the want of surface 
vegetation and the pebbles rolled into it. In all these it 
was manifest, that the fissure teas tlie evidence of a great 
earth slip, and had resultcdy not from any direct rending 
asunder of the ground or rocks beneath it, hut that th^ clay 
masses had wlien shaken violently upon the inclined beds of 
rock upon ichich they were superposedy slid down bodily by 
gravity, ami jmrted off from each other at these fissures. 

The fissures, by their direction, perfectly sustain this 
view, but arc absolutely opposed to the idea of fracture, 
either by shock or ))y uueciual or local sudden elevation or 



THE MECHANICS OF THEIR FORMATION. 265 

depression of the subjacent formations. For the great direc- 
tion in lenffthj of the fissures, is not far from that of the toave- 
path here, while it is everywhere but little removed from 
one, transverse to a line up and down the slope of the hills. 

The people generally stated, that these fissures were at 
first, from one to two palms wide, at the widest, and that in 
steep places, one of the lips was about a palm above the 
other, and that in one place, the depth had been probed 
with a rod to nearly thirty palms. The fissures evidently had 
in no case run down plumb into the soil, but sloped in the 
same direction, but with a less angle to the vertical than 
the hill side on which it was found. 

There is hence nothing very surprising in their occurrence. 
They are all in deep soft diluvial clays, of great specific gra- 
vity, very fine grained, and almost free from gravel and stones 
— a tenacious clay loam, that when wetted gets at once into 
a sticky paste, and soon runs into a greasy cream, so that 
a very small declivity and moisture alone, produce frequent 
land slips. Thus on the road leading from Auletta, along the 
slope of the hill, towards Villa Carusso, (which is also that 
to Salvitella and Vietri,) on the N.W. side of the valley, I 
observed a place where a slip had occurred, upon a bed of 
not above 12° or 15° slope, which a year or two since 
had carried away the whole road (here on side cutting), 
and lowered its surface about 4 feet, for some 400 feet in 
length, carrying with it the telegraph poles, still standing 
fast in the soil. 

But a small effort of vibratory movement, therefore, 
must be sufficient partially to dislodge masses of such 
material, on much steeper slopes. The average slope of 
the rock, beneath the soil of the great fissure here, cannot 



266 ORIGINATED BY A SMALL EFFORT, 

be less than 25"" to the horizon^ and may be much more. 
That of the fissure / is still steeper. The " work done " by 
the shock, in ariginaiing the actual transport of material, 
due to these fissures is not very large ; it amounts merely 
to reducing the friction and coherence of the mass, so 
as to permit the descent, through probably not more than 
3 inches vertically, of several millions of tons of earth, 
the movement of descent being produced by gravity only. 
The rain cuts these deep clays, here, (as everywhere in 
these provinces) into deep ravines or "nullahs." Some 
which I crossed in walking from the town of Auletta to 
Villa Carusso, which I next visited, were 30 to 40 feet in 
depth, with sides so steep and soil so greasy, that it was 
with great difficulty they could be crossed, and were it not 
for the hold on the brushwood at the sides, could not be 
ascended at all. 



CHAPTER VII. 

VILLA CARU880 — FIRST DETERMINATIONS MADE OF WAVE- 
PATH's EMERGENCE — PERTOSA — SOUNDS HEARD. 



The Villa Canisso is a large proprietor's house, visible 
from Anletta summit, at a distance of about Ih mile in a 
right line ; and seeing by the glass that it was a strong 
well-built house and nearly cardinal, I resolved to examine 
it. It is in general plan a parallelogram, with four towers 
at the angles, and a projecting sort of porch over the front 
and rear entrances. 

Its longest axial line is 110° E. of N. The western end 
is probably 400 .years old, part of an ancient semi-fortified 
ch&teau, and the towers here are of decayed and very 
inferior masonry. The remainder is modem, and of 
tolerably good uncoursed rubble limestone masonry, the 
stones not above 10 to 15 inches average bed, with dressed 
ashlar window and door jambs, and some Italian brick- 
work in the arcades over the south entrance. (See Figs. 
139, 140, 141, and Photog. No. 137 bis, Part I.) 

The walls at the west end appear to be about 2 feet 
9 inches in thickness at about 10 feet from the bases, as I 
found by climbing up to one of the window apertures, that 
shown in Fig. 141, north elevation of tlie tower, V, Fig. 139. 



268 



VILLA CARUSSO. 



No one was to be found, and the house was tenantless, 
so I could only make external examination. 

The only fissures are those marked //, &c., in the west 
end, all in the ancient towers, and two fractures in the 
slender brickwork of the southern arcades. The towers 
have been thrown westward, off from the body of the 
building, and the fissures at the reenterant quoins are 
2 1 inches open at top, and run nearly from top to bottom 
of the walls, which are about 32 feet in height to the 
eaves, and the whole of the west end is out of plumb. The 
fissures in the south front are seen in Photog. No. 137. 
Their direction has been determined and limited at the 
quoin, by the form of the buttress built into it, for nearly 



a 



9 




Fig. 139. 



half its height, and projecting at the base, as seen in 
grouud plan, Fig. 139. 



EMEKGEMCE HERE DETEBMINED. 2G9 

The fissures at the intenial flanks of the tower, that, T, 
(ground plan, Fig. 139), looking south, and that, V, looking 
north, are pretty exactly sketched in Figa. 140 and 141. 




Fli,'. 140. 



Fig. 141. 



These fissures slope about 30' from bottom to top towards 
the east, but they, like the preceding, have been rendered 
more nearly plumb, by the action of the buttresses and 
other disturbing causes acting in the interior, which I am 
unable to examine particularly. 

Some roof-tiles have been thrown from the eave at the 
west end, from p (Fig. 140), and are lying at m, from 
7 to 9 feet horizoutally from the base of the wall, having 
fallen vertically 33 feet. 

Taking the horizontal range of projection here, a = 9 
feet, and the vertical descent from the point jt>, 6 = 33 
feet, and assuming the velocity of projection V to be 
13 feet per second (which is about what it proved to be 
elsewhere in this neighbourhood), and solving for e = the 



270 FISSURES OP THE GATEWAY. 

angle of elevation of the projectile which is here equal to 
the angle of emergence, we have. 

Tan . = 2H±,/4 H(H+irr? 
a 
in which H is the height dae to V, and finally obtain 
e = 68° 25', for the angle of emei^nce, or that of tiie wave- 
path with the horizon ; but as the tiles were fastened more 
or less, some force was expended in detaching them, so 
that the angle e, was rather less than this, and may be 
estimated about 60" or 64°. 

The house was approached by an arched gateway, of 
rubble stone-work plastered, as seen in Photog. No. 138, 
looking south from the military road. This arched struc- 
ture is heavily fissured, right through the crown of the arch, 
showing most at the south side, and in three diagonal 
fissures on the north side of the structure. The largest 
fissure is about 4 inches wide at top. The gateway is 
12 feet wide and the height to the soffit is 16 feet; each 
pier is equivalent to about 4^ feet square in horizontal 
section, and buttressed by the fragments of walls pro- 
ceeding from them at each side. These fissures, like those 
of the main building, indicate a wave-path not far from E. 
and VV., and a direction from the eastward — on the whole, 
about 100° west of north. The gateway fissures have had 
their directions mainly determined by those of the vousaoire 
of the arch, which is of brick •, by the relative support given 
by the side walls as buttresses ; and by the rocking of the 
piers as the shock passed through them ; so that no inference 
can be drawn from them as to the angle of emergence. 

In the Photog. No. 138 the rcre or north front of the 
villa is seen, and above the projection at the central part 



BMERQENCE GIVEN BY VERANDAH. 271 

(which correspoDds to that above the *' Portone " of the 
south front) stood, before the earthquake, a wooden sort of 
verandah, framed, as shown in Fig. 142, and covered by a 




Fig. 142. 

prolongation of the slope of tiling of the roof. The whole of 
this had been thrown down, and was lying on the ground at 
and about the point s (in Figs. 139, 142, and Photog. 
Ko. 138) in dislocated fragments, from which, collecting 
and laying together the timber-work, I was able to recon- 
struct the design of the fabric. 

The shock emerging from the eastward had swept over 
the vertical posts towards the direction of the dotted lines 
nnuTi, and the tiling of the roof had rent away from the 
rest at the line of the eave r r, twisting and drawing out 
the cross lintels from their sockets in the walls of the house 
at the eaves, the whole mass then falling in the direction of 
ms. The weight of the timber-work was insignificant, the 
chief mass was in the heavy tiling which it carried. A 
line drawn from the position of the centre of gravity of 
this (the projecting tiled roof) to the centre of gravity of 



272 VIEW OF THE GREAT VALLEY FROM AULETTA. 

the mass of rubbish upon the ground, I found made an 
angle of 60° with the level ground. This is, therefore, 
about the angle of emergence ; but as the roof received a 
small amount of nearly horizontal motion at its centre of 
gravity before it began to descend, this angle is a little too 
small, and so it may be taken as about 62° to 64°, coin- 
ciding as thus separately determined, with the emergence 
as given by the tiles projected from the tower. 

The villa stands upon deep clay, upon the north side of 
the Auletta valley, the land sloping gradually southwards 
with a rolling surface, and behind it still further north, 
the limestone mountains (apparently Apennine limestone) 
rise with a flowing sweep to perhaps 1,500 feet, with 
bedding nearly parallel to the face of the slope, and a strike 
in the line of the axis of the valley, or E, and W. and 
north of E. The calcareous breccia is probably the rock 
directly under the clay on which it stands, however. 

By barometer I find the ground at the villa is about 110 
feet above the summit of Auletta. Returning from the villa 
to Auletta, a good view is afforded to the N. W. and W. down 
the great valley, which I sketched. Castelluccio is visible, 
perched upon its summit in the centre, and the lower ranges 
of the shaggy wooded precipices upon the north flank of 
Monte Alburno, block up the left of the view. Contursi is 
just visible upon another very distant height upon the 
right, (c) and the villa Carusso is seen at the .'oadside at (6). 
I proceeded on to 

Pertosa. — It also stands upon the top of a mound, less 
lofty and steep than Auletta, and not so elongated in 
form. The longer axis is on the whole transverse to the 
course of the Tanagro, or about SO"" E. of N. The steep side. 



-■-■.:!Ki: .■:»>^. 



W<ei-„ 






>-RnM. THt PLAIN 




f]l 



PERTOSA. 273 

faces towards PoUa, or towards the S. and S.E., and the 
gentler slope towards Auletta, or N. and N.W. The steepest 
slope is about 55° from the vertical. The " coUine " con- 
sists of solid beds of breccia of great thickness, of pebbles 
chiefly calcareous, but with many metamorphic hard slaty 
md chertose pebbles, of from 3 to 5 inches diameter, in a 
jalcareous cement. Beneath the town these beds have 
I, general E. and W. strike, or lengthwise to the river 
ralley, and a dip of 30° to the S. and S. E., so as to be not 
rery far from parallel to the faces of the limestone 
nountain slopes, behind them to the N. and N.W. 

The town was an extremely poor place, the land of the com- 
oune being less productive than that of Auletta, and chiefly 
he residence of working peasants. With the exception 
>f a few new houses, low, and tolerably well built, with 
Iressed quoin stones and jamb linings in long blocks, which 
lave stood pretty well, though heavily fissured, all the 
emainder of the town was built of large oblate or ovoid 
alcareous boulders, of from 10 to 12 inches across, picked 
)ut of the banks and river bed below, and laid into the walls 
IS in Figs. 143 and 144 (Coll. Roy. Soc), without an attempt 
it dressing flat-beds upon them, and with thick mortar joints. 
The town has hence suffered fearfully and is almost com- 
pletely demolished. The timbers of many of the houses 
titer their overthrow took fire, and more than 150 corpses 
>f the vast number buried in the ruins here, were found 
iharred and calcined when disinterred, and in some few 
ases, all semblance of humanity, fi'om the action of the 
[uicklime produced from the calcined limestone, absolutely 
bliterated. 

It was very painful to witness the subdued and patient 

VOL. I. T 



274 SURVIVING INHABITANTS. 

endurance of the survivors, exposed to the terrible incle- 
mency of the winter nights here, and the processions of 
women and children, carrying about some paltry relic, and 
whining litanies to the Madonna, in tones of despairing sad- 
ness. The recent visit as far as this spot of the deputation 
of Englishmen who came to distribute personally, the alms 
collected at Naples amongst our countrymen, was fresh and 
grateful in the memories of these poor beings, who crowded 
round me and struggled unwelcomely, to kiss my hands 
and pour " benedizioni " on all ^ Inglese *' to such an extent, 
that had I not fortunately found the Padre, Vincenzio Man- 
cini, I should have been unable to make any observation. 

He was a man of much more than the average infor- 
mation and intelligence of his class, but conversed in no 
modem language except Italian, which was strongly provin- 
cial, and I found it difficult to follow him ; he spoke Latin 
with some fluency and elegance, and I obtained from him a 
good deal of information. 

The town has suflfered most, at the east and west sides, 
the southern end the least. Large portions of the west side 
are a perfect chaos of ruin, and beyond reach of obser- 
vation or analyzation, as in Photog. No. 146. The general 
character of the west side is seen in Photog. No. 147. 
The Photogs. No. 148 (Coll. Roy. Soc.) and No. 149 
arc views at the southern entrance near the town and 
towards its central part. 

Those No. 150 (Coll. Roy. Soc.) and No. 151 give a 
tolerable notion of such portions of the town, as presented 
measureable elements of the direction of shock. The 
sketch No. 152, taken on the spot, shows a part of the 
west side in which the lines of street and houses were for 



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F^ . 



LEANING WALLS AMIDST THE RUINS. 275 

a certain range nearly cardinal. The walls a and by and 
all parallel to them, run nearly E. and W. These were in 
great part, more or less standing, but fissured, in sloping 
cracks; bat the walls whose plane had been N. and S. 




were universally down and in rubbish, unless something 
had accidentally propped them up. In the sketch No. 152, 
the gable wall a, had been built within about 2^ feet S. of b, 
a passage had probably run between them ; b was kept 
up by flooring and other props to the northward, but 
a had swayed over at top to the northward, and leaned 
against b there, the bottom of both being buried in 
rubbish wherever the fracture had occurred. 

The horizontal force and velocity with which a had been 
brought over against ft, was small, as they only touched, 
it the top, and the space below was all hollow between, and 
yet a was not fractured by the coming in contact : it was 
ibout 2 ft. 3 in. thick and about 15 feet hi^ above the 
rubbish. The sockets of the joists, whence they had been 
irawn and twisted oat, were still visible on its face. 

t2 



276 WAVE-PATH— THE EMERGENCE STEEP. 

The direction of wave-path given by all this portion of 
the ruined town, was from E. to W. 118' to 120° 30' W. 
of N. The force in the N. and S. direction, therefore, which 
brought the wall a against b was necessarily small. In 
some other portions of this west side, the crooked streets 
brought the general position of the houses to be ordinal, 
nearly 40° W. on the average. The houses that were so 
circumstanced, were less absolutely demolished than those 
whose front and rear walls ran nearly cardinal or N. and S., 
but diagonal and crossing fissures were to be found in all 
directions, and huge wedge-shaped masses, as in sketch 
Fig. 144 were thrown out from the W. and S. W. quoins 
of numbers of them. From the extent to which de- 
struction had proceeded, and the vile class of the masonry, 
measurements of the widths of fissures, were uncertain and 
the angles of fracture ill defined. From measurements and 
general judgment together, however, it appeared to me that 
the angle of emergence here, must have been extremely 
steep, steeper than the indications at the Villa Carusso, and 
certainly not less than 70^ with the horizon, possibly as 
much as 75°. 

■ 

This is corroborated by the nearly universal fall of the 
tiled roofs and heavier floors. 

In the Photogs. Nos. 149 and 150, some of the steeply- 
inclined fracturing is visible : some of the temporary roofs, 
as well as the piling up of the stones seen in No. 150, had 
been work done since the shock, in digging out for inter- 
ment, the buried corpses. 

At the east side of the town, the wave-path was more 
nearly E. and AV., and gave a general direction of 83° 30' 
or 84^ W. of N. 



WHY SOUTH SIDE SUFFERED LEAST. 277 

At the south portion of the town, the destruction was 
rather less than over the remainder. An obvious reason 
for the fact is afforded, now that the wave-path is 
obtained. The plane of the great breccia beds upon 
which the whole stands, is not very far from being at 
right angles to the direction of wave-path; hence the 
southern portion of the town received the blow through 
the greatest thickness of these beds, and thus, by the nu- 
merous and successive changes of medium, in passing 
fi'om bed to bed, the force of shock here had sustained the 
largest amount of loss of vis vivd. 

The direction, of the longer axis of the hill on which the 
town was perched, also accounts for the greatest damage 
having been done at the E. and W. sides, and less upon the 
very top and more level portion of the place. 

Nobody here nor at Auletta seems to have felt any second 
shock, occurring within a minute or two after the first; but 
they all speak of a second shock much less powerful than 
the first, but occurring about an hour after the first; 
testimony which appears strangely inconsistent with that 
universal at Naples. The Padre Mancini is positive, that 
there was no second shock soon {i. e. within a few minutes) 
after the first, of a noticeable character. He himself had 
escaped the first with diflBculty, and only owing to the 
fact that he was not in bed, and so was able to rush out 
instantly. 

As to the time of the shock, he does not know of any 
clocks having been stopped, inasmuch as there are none 
either here or at Auletta. He thinks it was at about 
a quarter past ten {tempo Framesi)^ i e. not reckoning by 
Italian hours. 



278 AZIMUTHS IN SOUTH ITALY— THE SOUNDS. 

According to his narrative, the shock was from S. to N. ; 
but when I caused him to point with his hand to what he 
deemed the north, he pointed nearly to the west, and I then 
found, what I afterwards recognized as the usual mode of 
speech in the provinces, that such words as " tramontana, — 
dal nordo, — meridionale, — mezzogiorno," were more com- 
monly applied to the apparent path of the sun in the heavens, 
from rising to setting, than with precision as signifying points 
of the compass. I henceforward always made the narrator 
point out with his hand the azimuth he intended. The testi- 
mony of the Padre therefore, which coincides with that of 
the postmaster down at the bottom of the valley, agrees 
generally with the deductions from my observations. 

Padre Mancini says, the first shock was " sussultorio," 
and immediately became " orizontale ed oscillatorio ;" and 
he thinks the second, of an hour after, was " vorticoso." But 
upon being pressed as to what he meant, he at length said 
" he thought the direction was not the same as the first, and 
changed while yet shaking ; but he was not certain," adding 
quaintly, that his own head and those of his parishioners 
had become " vorticosi " from the alarm of the first shock. 

The accounts given here and at Auletta, of the sounds 
heard at the same time, or rather before the shock, agree in 
the main. At Auletta, those who were in the town and sur- 
vive, commonly used such words as ^' fischio sospirante," 
and the like, in describing the sound. Those down at the 
Locanda geneixilly said it was like the " romore di carozzo " 
simply. The Padre <lescribed it as " ronzio e romore 
modeixito." And when asked more minutely to describe 
it, he said it was " ingens fremitus retonans cum sibilatione." 
My linal inipressioa was, that the description of the people 



WAVE-PATH AND EMERGENCE FROM CASA COMMUNALE. 279 

in the bottom of the valley, conveyed the notion of a more 
confused sound, than that of those on the summits, in the two 
towns ; as if echoes or secondary sounds from the precipitous 
sides of the hills around had in some way been heard more 
by the former than the latter, with the primary sounds. 

Descending with Padre Mancini, from the town to the 
road at the valley bottom, which is perhaps 100 feet above 
the bed of the Tanagro close beneath, I examined the 
little Casa Communale, a nearly new building (about three 
years old) a parallelogram of two stories (Fig. 153), nearly 



PUui, 




Fig. 153. 

cardinal (axial line 10° W, of N.), built of good rubble, 
with cut stone jamb dressings, and middling quoin stones, 
and with a heavy external stone staircase on the west 
flank. It was fissured in several places, and the fractures 
gave a wave-path of 120° W. of N., and an emergence of 
about 65° with the horizon. The emergence might be 
steeper, however, as the direction of the fissures in the 
front, had been coerced in some degree, by the large pro- 
jjortionate surface, of cut stone jamb dressings. 



CHAPTER VIII. 

THE GALORE AND TANAGRO — ST. MICHABL'S OAVB — 
GBOLOGT OF THE Y ALLEY — 0AMPO8TRIKA — GBBAT 
ROOK FALLS. 

AccoHPANiED still by the Padre, I then crossed the riYer, 
and scrambled up the opposite bank, composed of deep 
day and boulders, with graYel, to the mouth of St Midiael's 
CaYC, from out of which issues that portion of the whole 
waters of the Calore, (as the Tanagro aboYe this is called) ; 
that entering the limestone at PoUa, at the upper end of 
the gorge of Campostrina, and finding its way by sab- 
terraneous channels, here debouches, and turning some 
primitive water-wheels at the Catalan forge, falls in a 
pretty succession of cascades to join the Tanagro again in its 
open bed. The mouth of this large cavern is probably from 
50 to 80 feet above the open bed of the river opposite, and its 
jaws present evidence of powerful erosion. There are large 
stalactites within, and at about 300 feet from the mouth 
further entrance is barred by the water, which issues from 
the cavern almost clear and pellucid, while that of the 
river below is as white as milk, with impalpable cretaceous 
matter in suspension. As the water of the Galore thus 
divided between the subterraneous and the open channels 
at PoUa is very muddy, and contains much calcareous 



SUBTERRANEAN DEPOSITS OF THE CALORE. 281 

sediment, it is obvious that that portion which passes 
through the subterraneous channel is filtered/ or at least 
deposits much of its solid material on the passage, and is no 
doubt now forming new and strangely situated beds of 
clayey limestone, within the cavernous heart of the mountain 
range through which it passes, and which here separates, as 
by a huge wall, the valley of the Tanagro, from the Piano 
di Diano. 

A short way within the cavern is a shrine of wood, 
with a rude plaster figure of St. Michael, of about three feet 
in height, in the interior. I found this * genius loci ' had 
been overthrown by the shock, and as the shrine is fastened 
up like a sort of cage, the figure was still leaning supine, 
against the back of the box at a slope of about 30° with 
the vertical The saint had fallen, in a direction from W. 
towards the E. The base of the image projected widely in 
front, but less at the rear, and the figure being of a very 
upright character, it had been thrown over by the first move- 
ment, to an angle beyond the range of recovery, by the 
return stroke of the wave, and so remained out of the per- 
pendicular. 

The velocity of the shock had been sufficient to upset 
the image, but had not been sufficient to overturn the square 
wood shrine or cage in which it was placed, and which 
was about 8 feet high and 3| feet wide in the E. and 
W. direction. A sufficient corroborative proof, of the 
steepness of emergence of the wave here^ is afforded by the 
stability of this shrine, near the top of which, was the stage 
on which the figure stood. An extremely small velocity, 
if horizontal, or nearly so, in direction, would have sufficed 
to overthrow the whole affair. 



282 GEOLOGY OF THE VALLEY. 

The volume of water delivered by the stream from the 
cavern, does not seem to be above one-twentieth that of 
the main open stream of the river below, which receives 
no tributary of importance between this and the other end 
of the subterranous duct, at PoUa. 

Close to this cavern, the northern end of the gorge com- 
mences, through which the open stream forces its way — a 
jagged, wall-sided cleft, betwixt precipices, of rather soft, 
ill-bedded, and cretaceous looking limestone, nearly white 
in fresh fracture, and whose mean height is probably about 
800 feet. 

Standing upon the left bank of the river, and 50 feet or 
so below the level of St. Michael's Cavern, one is enabled 
to see with some clearness, the geological relations of the 
main valley and of its lateral ranges, which in transverse 
section here (looking southward) are approximately shown 
in Fig. 154. The Apennine limestone of Monte Albumo 
and its associated range, dips to the south-west and south, 
but with a constantly varying angle of dip. What is the 
connection of the beds, of the opposite or eastern chain, with 
those at the bottom of the valley, is not traceable ; it may 
be one of disunion and dislocation, as the existence of the 
gorge of Campostrina would suggest ; but the beds look, 
upon the whole, to be parallel continuations at the east 
side, of those deep under Monte Albumo upon the west. 

Above these in the valley, lies the coai^se calcareous 
breccia, in beds approaching conformability at the east side ; 
but where visible through the telescope, at the summits of 
the underlying mnges, on the west side, appear to be wholly 
unconformable to the escarpments of Alburno. Small but 
irregular valley bottoms, are formed at both sides, between 



GEOLOGY— CAMPOSTRINA. 283 

the underlying summits of the breccia mountains, and the 
flanking chains beyond; and in these, as well as in the 
bottom of the main valley, a great depth of loose material 
is deposited, chiefly heavy calcareous clays and boulders. 
These are deeply cut into by the lateral torrents, and still 
more deeply by the Tanagro itself, which here rolls over a 
bed wholly of rounded boulders, the skeleton of the 
washed-away detritus. 

It is not easy here, or indeed anywhere else in the 
Southern Apennines, to imagine the train of causation 
(upon any of the usually accepted views of elevation) that 
led to this formation. It seems probable, however, that 
before this upper part of the valley assumed its present 
character, the surface of the breccia occupied something of 
the line d cZ, &c., if not one still higher, and that enormous 
masses have been removed by denudation, between those 
which now form the opposite ranges of " Collines." As 
respects our immediate subject, it will be obvious that any 
earthquake shock, emergent from the eastward at a steep 
angle, must arrive, through an immense thickness of beds 
of limestone first, and of breccia afterwards, before reaching 
the surface; and hence with vast loss of vis vivdj and 
buflFed, as to much of its destructive power. 

I was unable to attempt determining, whether the 
breccia beds lie directly upon the limestone at both sides 
of tlie valley, or may have some other thin beds interposed. 
But I think the first is the fact. 

The military road of Campostrina, over the rampart that 
separates the valleys of the Tanagro and of the Galore (as 
its higher stream now is called), is led over the mountain 
at the eastern side of the river gorge, winding round 



284 CAMPOSTRINA— VIADUCT— GREAT FALL OF ROCK. 

several lateral valley-gorges, and crossing the principal 
one by an imposing viaduct of considerable altitude, built 
of ashlar limestone, and carrying a narrow road, over a 
double range of semicircular arches, upon piers overloaded 
with material and buttressed out, transversely to the width 
of the road, to more than twice its breadth at their deepest 
bases. This viaduct must have received the shock very 
nearly transversely to its length, but emergent at a high 
angle. It has sustained no damage whatever, though a 
top-heavy mass, a sufficient proof of the value of good 
masonry in an earthquake country. Padre Mancini po- 
litely accompanied me on foot to the summit of the pass, 
about 2i Italian miles, to point out the site, of an enormous 
fall of limestone rock, which had been produced by the 
shock. 

The general direction of the deep narrow gorge, in the 
bottom of which the foaming torrent of the Tanagro rolls 
for several miles along, is nearly N. and S. The limestone 
beds at either side, as well as the jagged serratures of the 
cliflFs, in many places vertical or overhanging, correspond 
to each other, and prove it to have been torn by separation 
of tie opposite mountain masses. 

The strike of the beds is nearly N. and S., and they dip 
at various angles, but all very steep towards the S. and 
S.W. The bedding is not very clearly defined, and the 
rock is lithologically, softer and more of a cretaceous 
character, than that of Monte Alburno, and may probably 
belong to a diflferent member of the limestone formation. 
No fossils anywhere met my eye, and other occupation 
precluded my looking for them. 

The first great fall of rock I found had occurred about 



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DAMMING UP OF THE RIVER COURSE. 285 

a quarter of a mile beyond the viaduct : its position is 
shown in Photog. No. 1 55, the view in which is taken, 
looking southwards, some of the revetment walls at the 
turn of the zigzags of the military road, mounting the 
hill, beyond the viaduct, being visible at the left of the 
picture. Near the centre of the view, where the white face 
of rock is visible, a mass of limestone had been thrown off 
in a S.W. direction, 69° E. of N., from the face of the 
cliff, and, shattering in its fall, had carried some thousands 
of tons of rock, small stone, and fine whitish debris, down 
into the bed of the river. The talus was heaped up at the 
base of the cliff, and stretched nearly across the whole 
breadth of the bed, forming a serious obstruction to the 
current, which was dammed back a good deal, notwithstand- 
ing the rapidity of its slope, and the torrent had already 
washed away large portions of the fallen mass, and as I 
watched it, was sorting out the finer material, and as it was 
removed slight falls of stuff continually occurred at the toe 
of the slope of debris, into the water rushing past its base. 

The Padre informed me, that for four or five days after 
the 16th December, the volume of water discharged at 
Pertosa, both by the open channel of the river, and by the 
cavern of St. Michael, was visibly diminished, he thought 
by as much as one fourth the former delivery, and both 
currents ran turbid and foul. The delivery of the cavern, he 
thought, was even now, less than what it had been before, 
but the open river had returned to its usual regimen, except 
in so &r as it was much whiter in colour, from the sus- 
pended chalky limestone, than he ever remembered it, 
though always more or less, so discoloured. 

I remarked that many other smaller falls of rock had taken 



286 INFALLEN ROOF OF THE GREAT DUCT. 

place, at various points of the gorge, and from the N. E. side 
of the lateral ravine, which is crossed by the viaduct, whose 
steeply inclined sides are in many places, covered with loose 
material and large angular boulder blocks. Several of these 
had been dislodged, and projected into the bottom, leaving 
in some cases the torn traces of their headlong descent, in 
furrows whose direction I found to be, about N. 15^ E^ 
the stones falling to the southward. 

On gaining the summit of the ridge, next above the 
viaduct, and looking to the S.W. across the gorge to the 
opposite mountain, I observed a very singular cavity 
in the slope of the flank, and at such a distance back 
from the edge of the cliflF, as would render it probable it 
may be vertically over, the subterraneous duct in the 
rock, carrying the water from Polla to St. Michael's 
Cavern. 

This is sketched in Fig. 156. It appears as if produced 
by the falling in of the roof, of a cavernous enlargement ot 
the subterraneous duct at this point ; and the mass standing 
up in the middle of the crater-like cavity, is probably part 
of the roof, tilted over in the fall, and sustained by otU^^ 
fragments beneath. The Padre said there was no water ^^ 
the bottom, nor any entrance from it to a subterranef^"^^ 
chamber, and it had received no alteration, that he ^r^^ 
aware of, since the earthquake. The cavity is probably^ ^ 
quarter of a mile long, from right to left in the sketch. 

Amongst the many lying wonders that were narrat^^^ 
about the earthquake, I afterwards heard it circumstantial 1^ 
affirmed that this, was a crater, had been formed at tl^^ 
time of the shock, and that fire had been seen to issue from i ^• 

At nearly the highest point of the road, I found tU^ 




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HEIGHT OP THE PASS— FISSURES IN THE ROAD. 



287 



barom. 28*09 in., thenno. 42° (14th Feb.), which, when 
reduced, gives the elevation =1913-4 feet above the sea. 
This proved soon after, however, not to be the very highest 
point, which I reached at about 150 feet higher. The total 
elevation, therefore, at the road is 2063-4 feet above the 
sea, and about 1420 feet above the piano of the valley 
bottom at Auletta. 

At the former point nearly, the road is formed upon a 
side cutting and small embankment, on limestone covered 
with 3 or 4 feet average, of arable clay land. It is sustained 
by an ill-built revetment wall of dry stone, with mortared top 
courses, in all about 12 feet high. The general direction of 
the centre line of the road is 30° W. of N., and nearly level. 
For a length of about 300 yards, an irregular longitudinal 
fissure was open, in the surface of the roadway, at about 
a quarter of its breadth from the revetment wall, of about 
3 to 4 inches in width, and in some spots still, 10 or 12 inches 
deep, though much obliterated and filled by rain washings. 





it 



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Fig. 157. 




The form of the fissure and section of the road, as sketched, 
are shown in Fig. 157. Three portions of the revetment 



288 OTHER GREAT FISSURES. 

had been thrown towards the west, and from the position of 
the fallen material, the direction of the wave-path proved to 
have been N. 140° W. The portion of the road to the west 
of the fissure, had slipped and descended about 4 to 6 inches 
below the former level, as shown in section b. It was im- 
possible to tell, whether the revetment wall had been founded 
upon the rock or not, but from the appearance of the ground 
at its base to the westward, I believed it had not : in any 
case, it had gone out at the base, towards the west, and with 
the mass of earth behind, had been severed from the remain- 
der of the road filling, and slipped at the same monfent. It 
is a case very analogous to the Auletta fissures, with this 
difference, that here, from the unsupported position of the 
road embankment and revetment, and the direction of the 
shock, the separation had much more nearly approached a 
"throw oflF" at the instant of shock, mixed with the move- 
ment of slip or descent. 

About a mile further on, just before the rapid descent 
commences into the Valley of Diano, another set of road 
fissures had been formed, where the road is also in side 
cutting, but slopes olT at the western side without anv 
revetment. Here the fissures which are shown in Photog. 
No. 158 are clearly produced by the slippage off to the 
westward, of an enormous breadth of the clay land, reposing 
upon a surface of limestone — sloping westward at about 
20° to the horizon — and with ])eds not much more inclined, 
and dipping in the same direction, circumstances all 
favourable to a large slip. The direction of wave-path 
shown, is about the same as the preceding. The telegiuph 
poles all along this portion of the road, I remarked, had 
been loosened in the ground, and thrown out of plumb, 



THE TENEMENTA DELLA MADONNA. 289 

and had not yet been again secured. Being restrained by 
the wires from rotating at the top, i.e., confined to vibrate 
in a plane not very widely departing from transverse to 
the length of the wires, they had not formed conical 
cavities at their butts, but such as would have been pro- 
duced by the pole, working forward and back, in a line not 
quite transverse to the length of wire, but, so far as its 
restraint would permit, also towards the south, so that on 
the whole their movement, coincided with the evidence of 
wave-path here given by everything else. 

It was doubtless this swaying drag upon the wire (it is 
but a single one) produced by the poles that broke the 
former, and so cut off all telegraphic intelligence, between 
the great earthquake district and Naples, for above forty- 
eight hours, during which the most intense anxiety was 
felt in the capital, as to the fate that had probably over- 
whelmed the provinces. 

Upon the highest summit of the pass is erected a little 
roadside shrine — the Capella della Madonna della Pieta, 
which was riven and fissured in a very remarkable manner, 
and only stood, by help of some pious props, that since the 
earthquake had been strutted against its tottering back and 
ends. It is shown in Sketch No. 159, made on the spot, 
and in Photog. No. 160 (Coll. Roy. Soc), taken some weeks 
afterwards. 

The plane of the front face of the "Tenementa," is 
north 45° W., and the fractures clearly indicated a wave- 
path having an azimuth direction of north 157° 30' W., 
or from the N.N.E., and having a very steep angle of 
emergence. The little structure was built, of coarse lime- 
stone rubble, plastered all over, and the cohesion of the 

VOL. I. u 



2fm IL VALLONE. 

mortar jointe but small. Applying to it the equation of 

overturning 

with the value for V, (ascertained next day) for the emergent 
shock at Polla, it is certain that the split-off portions 
above b and c, would not have rocked and returned to their 
places as found, but have been completely overturned, had 
the wave-path been at a less angle to the horizon than 61° 
nearly. The angle of emergence here, therefore, must 
have been as steep as that, at least, and may have been 
steeper. 

Looking back from this point, and sweeping the moun- 
tain side to the westward of the gorge with the telescope, 
[ see a large Casale — upon the slope of the hill distant 
about four miles — almost in ruins, and can plainly discern 
by a favourable light, that it has been overthrown by a 
shock, which there, had the same general direction as here. 

The direction of the slope of the hiUs at both sides 
towards the southern entrance to the gorge, begins to 
change and to trend round to the S. W. ; and a little further 
on I catch the first view down upon the grand Vallonc di 
Diano, its plateau level as a sea, stretching away twenty- 
six miles to the south, and four or five miles wide, the 
( -alore, folded along upon its central surface like a silver 
cord, losing itself in distance, and the mountains rising 
almost abruptly from the piano at either side, the further 
end closed in and surrounded, by pile over pile, of dark 
grey mountains and snow-clad sierras, at last shutting out 
the horizon. 

I can now perceive that Campostrina gorge, is the hinge, 



POLLA. 291 

between the two valley systems, and that the valley I 
have left^ and that I am about to enter, have their re- 
spective axes almost at right angles to each other, the 
pivot round which they wheel being the mountain mass 
behind the town of PoUa, and to the S,W. and W, of it 
The descent now becomes rapid, and after another mile or 
so, Polla becomes completely visible, the dominant town 
of the north end, of the wealthy plain, along whose east and 
west sides I begin to discern many others. 

Polla was an important place ; originally, as its name 
imports, one of the ancient foundations of Magna Gnecia. 
Nothing older than middle-age architecture remained, 
however, before the earthquake, and of this the Castello, 
near the summit of the town, was the most prominent. Its 
position in the rich country around, had produced its rapid 
modem growth to nearly seven thousand inhabitants, and 
most of its buildings were comparatively modern and pretty 
well built. Its streets and houses, churches and belfries, 
with olive yards and gardens between, spread themselves 
over the crown and slopes, to the north, south, and east of 
the large, low, short and well-buttressed spur of solid lime- 
stone rock, which juts out from the mountain range at the 
east side of the Vallone di Diano. The lengthway of this 
spur, is rather transverse to the general line of the valley, 
and its steepest side is towards the south. The city looked 
down upon the Calore, slowly and deeply sweeping past its 
eminence, and upon its own suburb of St. Pietro, at the 
opposite or right bank of the river, connected with the 
city by a fine old bridge of Eoman style, and to the south- 
ward it gazed for miles over the glorious and unbroken 
hill-girt plain. 

V 2 



292 ITS DESTRUCTION 

Its position and appearance are seen in Photog. No. 
161. (Vick Frontispiece.) As I descended towards 
it, huge yawning gaps began to show themselves, upon 
the northern and southern slopes, where for acres in 
extent, everything had been levelled, all traces of streets 
annihilated, and where they had been immense mounds 
and sloping avalanches, of white and dusty stones and 
rubbish, filled up and encumbered the ground. Between 
these, shattered and bowing fragments of walls, and torn 
remnants of once lofty buildings^ stood in mighty con- 
fusion ; beams and rafters, tossed up like the arms of the 
despairing, stood out hard and black against the pallid 
heaps. The words of the Hebrew bard, referring to a still 
more eastern scene of earthquake energy, recurred to 
memory with a strange reality — " How is the city become 
an heap, the defenced city a ruin." Months of bombard- 
ment would not have produced the destruction, that the 
awful shudder of five seconds involved, when thirteen 
hundred houses fell together with deafening crash, and 
overwhelmed above two thousand of their sleeping in- 
mates, and with clouds of suffocating dust, choked the cries 
of horror and anguish, that rose from the startled and 
often wounded survivors. In three difierent directions, 
conflagmtion soon added its terrors to the scene, and 
beamed up, a flickering and ominous light, into that dread- 
ful night of cold and wailing, throughout the lingering 
hours of which, in helpless agony, they listened to the pas- 
sionate entreaties for relief, the dying sobs, of relatives 
and friends entombed around them, and dreaded for them, 
more than for themselves, the recurrence of other shocks. 
The cold gray light of winter^s dawn, obscure with smoke 



AND TEPROKS. 2\)ii 

I dust, revealed hundreds bruised, or with broken limbs, 
;hout a roof to shelter them, many without a garment to 
rer them. 

[t required some hours' familiarity with such scenes, 
ore the mind assumed sufficient composure and cai)ability 
ibstracting the attention, to pursue the immediate objects 
my inquiry. 



CHAPTER IX. 

THE OBSERVATIONS AT POLLA AND ITS 

NEIGHBOURHOOD. 



Upon the south and north slopes of the town, I clam- 
bered over heaps of stone and rubbish, and amongst 
entangled beams, ten, fifteen, and even twenty feet in 
depth, above the former surface of the place. Upon the 
eastern slope the ruin had been less; but over the 
larger portion of the city upon the hill, the destruction had 
gone so far, that objects suitable for the dcterminatiou of 
the precise direction of the shock no longer existed. 
Viewed with a comprehensive glance, it was obvious that 
the shock had been in a direction not far from north and 
south, and had been very steeply emergent. The Photogs. 
Nos. 162 and 163 (Coll. Roy. Soc.) convey some faint idea 
of the general appearance of the more completely over- 
thrown portions of the city ; and those Nos. 164 and 105 
(Coll. Roy. Soc.) of the character of the ruins seen from the 
midst of them. No. 164 is a street of the more level part 
to the east of the city ; No. 166 (Coll. Roy. Soc.) is amongst 
the heaps that overwhelmed the site where the church 
Santa Trinita had stood; and No. 165 looks upwards over 
a quarter of a mile of ruin, towards that of the Castello tliat 



SANTA CHIARA. 295 

stood upon the summit, and under the masses of which 
many of the gendarmerie were crushed. 

Wherever the walls had stood sufficiently, to observe the 
direction of fissures, they were found traversing the former 
at angles indicating steep emergence, as may be seen in the 
three last Photogs. In general, however, this angle ap- 
proached the vertical more, at the upper parts of the city, 
than at or near the base of the hill on which it stood, 
proving that whatever had been the angle of emergence of 
the wave, at the base of the hill, or on the level of the 
plain, the hill itself short and stumpy though it was, had 
vibrated with a proper motion of its own, which, being 
necessarily nearly horizontal, had thus modified the angles 
of the fissures. Descending by the east slope, and amongst 
the buildings around the base of the hill, and towards the 
bridge over the Galore, I found abundance of objects for 
fixing the direction of wave-path. 

The church of the monastery of St*. Chiara (Photog. 
No. 167) stands about half-way down the slope. The plane 
of the west end wall is exactly cardinal (north and south), 
and shows large diagonal fissures running quite across the 
fa9ade. The direction of these proves a wave-path, north to 
south lO'^ to 12** E. of N., and an angle of emergence not 
less than 40^ The support of the solid belfry at the S.W. 
quoin, has prevented fissures crossing each other in this 
end, and, with the exception of one great diagonal shatter- 
ing, at the top of the belfry, its construction, has involved 
chiefly a deep vertical fissure in it, extending almost to its 
base, but at the east end. The diagonal fissures of the 
main building, cross and have their upper ends inclined, 
chiefly towards the north. The roof has in great part 



29G MADONNA OF LORETTO. 

fallen in, and such portions of it as still indicate the 
direction of throw, prove it to have been from S. to N., 
at an angle downwards of 50° to 60° with the horizoD. 
Two small and slender iron crosses, one on the top of the 
pediment over the west end, and the other on the belfiy 
top, are bent over, the former to the north to about 15* 
from vertical, the latter to the south, about 25° from 
same. I found I could not reach these, to get the scant- 
lings of the iron, &c., as measures of velocity ; the ruins 
continuing to fall at unexpected intervals, and the height 
being considerable. The belfry cross, by the theodolite 
telescope micrometer, appears to be about 2 i feet high, and 
of iron, about If x f in. section, and is bent on the flat. 

The church of the Madonna of Loretto was a solid 
Corinthian structure, still lower down, and in great part 
built of brick, with heavy semicircular arches, to the nave 
and aisles, and a heavy semicylindric roof; its axial line 
cardinal. As may be seen in Photog. No. 168, it is fis- 
sured down to its base, the fissures (some of which, of a 
regular and measurable class, may be observed under the 
altar-i)iece at the N.E. corner low down) all indicate a wave- 
path from north to south, and in direction about 100° 30' W. 
of north, and an emergence of 50° to 60° with the horizon. 
The north flank wall, leans heavily out towards the north, 
as do all the large sashes still standing, high up in that 
wall. The main mass of the rubbish of the fallen roof, \B 
in the inside of the church, and towards the north side oC 
the floor. The shear or l)rcak of the roof vault also proves 
the direction of the force of fracture to have emerged from 
the north at a steep angle, as may be seen in the Photog. 
No. 168. On the right side near the pulpit, may be seen 



ST. DOMINICO. 297 

wooden Roman-Doric pillar, the base of which was fixed 
ito the flagged floor, and which carries on its top a wood 
lobe surmounted by a small gilded cross. The two last are 
ent over upon the iron spindle that confined both, towards 
le south in a plane very nearly north and south. This 
robably was produced by the second half vibration of the 
ave, but may have resulted from a blow from some falling 
ody. The spindle or bolt that held ball and cross, was 
bout f in. diameter ; the ball about 8 in. diameter ; and 
le cross rose about 15 inches over it. I could not get 
s weight, but both it and the column were of hard wood, 
'his church was built after the earthquake of 1652, and 
ith special reference to future shocks. Iron chain bars 
ad been built into the arches and roof, and would no doubt 
ave done good service had the shock been more horizon- 
il, but its direction of steep emergence took them trans- 
ersely, and in several instances tore them across. The 
•actured ends of one, may be seen projecting from opposite 
ides, of the fallen roof-vault, and corroborate all other 
vidences of the steep emergence of the wave here. 

Photog. No. 169 (Coll. Roy. Soc.) shows th'e interior of the 
hurch of St. Dominico (?), attached to a monastery a few 
undred yards from the last, and looking westward. This 
ras a much worse built church, and of stone. The direc- 
Lon of the inclined fissures may be seen, inclining north- 
rards at their upper ends, in the west wall. The line of 
•acture of the arched groin of the roof at the south side, 
s well as the mass of the fallen material of the roof thrown 
3 wards the opposite or north wall, all prove the same 
eneral direction of path and steep emergence. 

Photog. No. 170 presents an arched wall in a north and 



298 ARCHES AND ROOF FALLS. 

south plane, 20^ E. of north, in the same monastery, and an 
example, of heavy dislocated, and inclined fissures. The 
average angle here was 45° to 50° from the horizon. On 
principles explained in Part I., this is below the actual 
angle of emergence, as here each pier rocked more or less 
individually, and with the direction of the voussoir joints 
tended to give greater perpendicularity to the fissures. 
The crown of the upper tier of arches had all fallen in, 
and they, as well as the cross wall seen to the left of the 
picture broken off, had all been thrown northward, as the 
marks of abrasion upon the plaster of the face of the 
arched wall testify. 

The Photog. Fig. 171 (Coll. Roy. Soc.) is an example of a 
frequent way in which arches are affected, indicating steep 
emergence. This arch is in a wall not far from north and 
south in plane. The ink lines c c point out the extremes of 
minimum and maximum angles of emergence of the wave 
coming up from the northward. The dislocation of the arch 
produces loss of momentary support to the crown, the top 
ring of which has descended some inches, bringing a mass 
of wall along 'with it ; but the fissure closing upon it at 
the second half vibration of the wave, has caught it, and 
the arch ring remains, nipped as shown, having descended 
through the space below its original intrados, at the point 
of intersection of the fissure, in rather less than the time 
occupied by one complete vibration of the wave. The 
data are not precise enough, however, to found calcula- 
tion upon with any certainty as to this short interval of 
time. 

The Photog. No. 172 (Coll. Roy. Soc.) looks N.W., and 
shows several tiled roofs fallen in, and is an example of the 








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CATERATTA OF THE GALORE. 299 

general character of roof fall, here and wherever the angle 
of emergence is steep. 

Descending still to the level of the plain, but not far 
from the hill of Polla, I found the most instructive 
examples. 

The Photogs. Nos. 173 and 174, are views of an isolated 
sluice-house, that stands upon the east or left bank of the 
Galore, and was intended for use in relation to irrigation 
works, connecting the river channel with an artificial one at 
certain seasons. 

In No. 173 the east side and north end of this structure 
are shown, and in No. 174 the west side and south end. 
The building is quite modem, constructed of good rubble 
masonry, with cut limestone quoins and jambs, flat window 
arches, and stone cornice over entablature. It is about 
30 feet high above the soflBt of the sluice arch, 30 feet 
wide north and south, and about 20 feet wide east and west, 
the walls 2 feet 6 inches thick. The building is exactly- 
cardinal, its longer axis N. and S. Referring to No. 173, 
heavy inclined fissures will be seen running fi*om both 
quoins, and meeting near the centre at top. The wall 
above the window arch is dislocated, and the voussoirs are 
thrown downwards, by a force emergent fi-om the north, and 
nearly parallel with the fissure c a. Several minor fissures, 
which do not show in the Photog., existed through the 
arch joints near (?, at 45° and 55° fi-om the springing (or 
horizon), and in nearly the same direction, diagonally 
throi^h the opposite or southern pier face. 

The north end wall (to the right in Photog.) is scarcely 
fissured at all. The whole of the blocks of stone of the 
cornice at the north end, have been thrown from ofiF the 



300 CATERATTA 

top, and falling not due norths bat some points to the east 
of north, upon the brow of the bank below, have rolled down 
into the dry bed of the river, and are seen lying about 
under c. The cornice blocks tailed in upon the wall, but a 
short distance, and were not far from being balanced over 
the front arris of the entablature, on which they were bedded. 
The force that overthrew them, therefore, was one emer- 
gent from the north towards the south, a few points to the 
east of north ; and from the position of the centre of gravity 
of the course of stones, it could not have been of steeper 
emergence than 70° to overthrow them, a line from that 
centre, at that angle, cutting the entablature arris. The 
roof had fallen almost completely in, and its debris of tiles 
and short timber, lay chiefly towards the north end of the 
interior. 

Referring to Photog. No. 174 of the west side, where 
the wall was much more uniform, as to aperture, &c., the 
great line of fissure will be observed, inclining at top 
towards the north, and crossing through the arch lintel of 
the doorway about the centre. The angles of these fissures 
were 30° to 34° with the quoin, giving an emergence of 
60° to 56° from the northward. The cornice was all 
perfect on the south end, as also on the east and west sides, 
except where fractured over the window at the east side, thus 
corroborating all the other proofs of steep emergence froii> 
the northward. 

A number of the entablature stones, laid with wretch — 
cdly shallow beds, (only veneered upon the face of th 
rubble hearting,) on the centre part of this west side, ar- 
seen fallen out. They were lying very near the base (^ ^ 
the wall, on the roadway that is seen here, passing over th 



OF THE GALORE. 301 

sluice and in front of the building above it, and they had 
been slightly projected, by the eastern element of the emer- 
gent wave, at the moment when they were relieved from 
the detent of the cornice above, by the giving downwards, 
of the central part of the wall over the door lintel, which 
will be observed also down. The south end was very 
little fissured, and the evidence was clear of a wave-path, 
not varying above 15° or so from the plane of the side walls, 
or north and south. 

The fissures were 2-25 inches wide at top, on the west 
side, and about 2 inches (in the same direction), on the 
east, which also indicates an eastern element of about 17° 
in the wave-path. 

Referring back to Photog. No. 173, in the foreground 
certain piers are seen — groove piers for inserting stop 
gates, to pond the water for irrigation in the dry season. 
These stood in about 4 feet water, were of sound dressed 
limestone ashlar, * and presented the long way of their hori- 
zontal section to the wave-path. Each pier was about 
10 feet long by 4 wide, and about 12 feet high; not a 
stone was dislodged. The top courses were cramped 
together. From their peculiar narrow figure a very 
moderate divergence of the wave-path, from the north and 
south, would have probably suflBced to dislocate, if not to 
overthrow them. 

Several other buildings of rather large size, situated 
about this portion of the city, chiefly * ordinal, gave by 
fissure, when reduced, a wave-path varying between 
157° 30' and 164° W. of north. It would be unprofitably 
tedious to give the details at length. 

One of the most instructive buildings at Polla, was the 



302 THE PALAZZO 

Palazzo Falmieri, situated not far from the bridge over 
the Calore, and nearly on the level of the plain. The 
west front of the house (i.e. looking eastward) is seen in 
Photog. No. 176 (Coll. Roy. Soc.), the central building in 
the picture, and to the left of it is the Capella Palmieri, 
forming a connected building with the palazzo, and with 
its west end ranging with the front of the latter. 

In Diagram No. 175, Fig. a, is a sketch elevation of this 
west front and block plan of the building. The house is 
exactly cardinal ; it is large, comparatively new, and 
tolerably well built, though of short lumpy stone, with 
much cut limestone about the quoins and jambs, &c 
It consists of a central court, surrounded by buildings of 
two stories and an attic, beneath the tiled roof. It is built 
upon the solid limestone rock, which at this point rises up 
through the deep alluvium, that lies around it at every side 
for a considerable distance. The ground is level around it 
except on the south, where it slopes off rather rapidly, the 
rock disappearing beneath the alluvium. It is, in fact, 
built upon the top of a sort of low pinnacle of limestone 
rock, that comes up (like many othei-s round the borders of 
the great plain) to its level, through the deep alluvium, so 
that it stands as it were on the top of a little subterranean 
"coUine," like a rock in an ocean of earth. The beds of 
the limestone here, as generally throughout the Tallone, 
are almost vertical, or at extremely sharp dip, and tend to 
a general east and west direction of strike. 

The nearest rock, upon the same level, appears again 
at about 200 yards above the bridge, where are those 
singular and picturesque " swallow holes " into and through 
which, a portion of the waters of the Calore disappear, to 



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PALMIERI. 308 

find their subterranean course to St. Michael's Cavern at 
Pertosa. There are several apertures, and the waters 
which before their plunge, turn some primitive old ** mo- 
linas," appear to fall to a great depth. The rock, where 
visible, shows extremely rapid erosion by the water, as 
well as evidence of immense dislocation and denudation at 
former periods, when the great valley was drained dry over 
it, by the gradual rending of the gorge of Campostrina. 

The Palazzo Palmieri is fissured diagonally in every 
ivall more or less, those in the north and south walls being 
he most formidable. A large wedge-shaped mass, carrying 
with, it a portion of the roof, is thrown from the S.W. 
juoin of the front, and a large portion of the south external 
vail, is prostrate and thrown to the south. 

In Fig. 1, Diagram No. 175, the form, position, and 
mgles, of the principal fissures found in the west front are 
ihown, looking eastward, entering beneath the " Portone," 
tnd looking back or westward. The fissures formed above 
.he archway in the north and south wall of the interior 
JBi^ade, parallel to the front, are seen in the Photog. 
Ho. 177, and in the sectional sketch (No. 178) taken on 
he line A B (on plan), and looking westward. 

The south external wall, ^ to ^, had been thrown to the 
oath, and the upper part lay between t and k. 

This is shown, in part, in Photog. No. 180 (Coll. Roy. 
Joe.), as seen from the balcony of the staircase, directly 
pposite the entrance gateway, and is shown in elevation 
DL Photog. No. 179, looking eastward. In all these the 
leneral directions and angles of the fissures are correctly 
ixhibited. There are some fissures, in all the walls, but 
he great mass are in those running north and south. 



304 THE PALAZZO 

These make angles with the vertical of 30° to 40°, They 
cross ill both directions, but the larger and greater number, 
are inclined at top towards the north. 

The fissures in the walls running east and west are all 
more nearly vertical, than those in north and south walls. 
They prove that the building rocked in all directions, but 
that the main force was one emergent from the north to- 
wards the south, at an angle with the horizon of between 
50° and 60°. The violence of movement in this direction was 
great, where, for example, one fissure passed through a joint 
of the arch, composed of long, curved, ill-formed voussoirs, 
at s (Fig. 178), over the front gateway, the arrises of the 
stones at the junction, are flushed ofif, as seen in enlarged 
Sketch (Fig. 178), and many such occur in the arches of 
the stone staircase, a square winding one, which, from its 
irregular form, is dislocated in every direction, as may be 
partly seen in Photog. No. 180 (Coll. Roy. Soc.) of the 
west interior facade. 

The external Avail ^^ at the south end, B on block plan, 
was built on scarped ground below the floor level. It had 
been about 38 feet in height, and was but little restrained 
by cross walls, and these only at the ends, about 70 feot 
apart, and was built of bad rubble (as is much of the 
Palazzo, though with costly cut-stone dressings, &c.), Id 
lumpy blocks, of 10 to 16 inches greiitest length, tlie 
mortar joints thick and bad, and no thorough bond. This 
wall was 2 feet 4 inches thick, and about 8 feet in height 
from the top, e to g (Fig. 178), was thrown outward, so 
that the great mass of the debris lies, in a parallel heap 
upon the sloping ground between k and ^, from 10 to 
18 loet from the foot of the wall, the average distance of 



PALMIERI— THE FLOORS. 305 

throw being 14 feet, and the height from which it had 
descended 30 feet, i. e., these being ordinates to the centre 
of gravity of the thrown mass. The portion thrown off 
from the top, was projected during the second semiphase 
of the wave, by the velocity impressed during the first, or 
by the return stroke of the shock. 

Let a = 80 feet, b = 14. Then from the equation 

a 

we find tan ^ = 1-593, and e = 57° 50', an angle of 

emergence which is within the limits given, by the fissures 

(which in this instance are extremely well defined in the 

Photogs. Nos. 177, 179, and 180, Coll. Roy. Soc.) in several 

parts of this building, and in that of the sluice-house at the 

river close by. 

I shall recur to this wall when treating of the " camine," 
thrown in the dining-room. 

Throughout the Palazzo, the floors are of beton and tiles, 

laid upon thick oak planking, crossing over oak and fir 

joists at about three feet apart : some in the largest rooms 

at the north wing, have been brought down altogether, the 

fractured beams showing, that they yielded to the inertia of 

the mass of beton and tiles, under the emergent wave. 

All are fissured, in various directions diagonally across, the 

lines more or less curved, with the hollow sides of the 

curves totoards the centre of the floor, and upon the whole 

making angles of about 22° 30' with their respective 

walls, and crossing each other towards the mid length, 

nearly at right angles; the great prevailing direction 

22° 30' E. of north, and at right angles to the same. These 

floor fissures, as nearly as they could be drawn by the eye, 

VOL. I. X 



306 



THE FLOORS. 



in one of the large reception rooms of the first floor, are 
shown in Fig. 181. 




Fig. 181. 

In the great drawing-room, the diagonal fissures in the 
north and south walls are 2, 2 i, and 3 inches wide at the 
ceiling level, in about 16 feet in height. And the brown 
planks of the naked floor above, (naked here, because all the 
ceiling has come down, and left the oak and chestnut bare) 
have drawn from the north wall, which has gone out, and 
the floor and south wall have gone together in the opposite 
direction, the total movement at the floor level being 
4i inches, and almost exactly parallel to the line of the 
cast and west walls. In another room, of 16 feet in length 
of end wall, the planking has drawn from the north end wall, 
4 inches at the east, and but 2 inches at the west corner, 

indicating a wave-path north and south, 
with some degrees trend to the east of north. 
The east and west walls being heavilj 
fissured, the south wall had gone out in 
the direction parallel to ac (Fig. 182). 
The Palazzo though thus shattered, and in many places 
dangerous to approach, had yet several articles of heavy 
furniture, &c., remaining untouched and unremoved; and 
through the politeness of one of the Palmieri family, 




Fig. 182. 



THE GAMINE. 307 

who attended me with his servants, and answered all my 
inquiries, I was enabled to make a more minute examina- 
don of the interior of the house, and to record some most 
instructive cases of disturbance by the shock, giving 
measures at once of wave direction and of velocity. 

Of these, one of the most valuable in deduction, is the 
overthrown stone and brick breast, of the " camine," or 
chimney hood, of the kitchen adjoining the great dining- 
room. This room was in the north wing of the building. 
The chimney hood was built, against the south side, of a 
wall running nearly east and west; so that a normal to 
its face, was north 10° E. 

The chimney breast, which is accurately represented 
fipom careftd measurements, in 6, &c. Fig. 175, consisted 
of three blocks of Apennine limestone ; two being vertical 
side jambs, and the third an imposited lintel, with a little 
brickwork superimposed, to complete the junction with 
the flue in the wall. 

Fig 6, 175 is the " camine," in front elevation, Fig. 6, 
&c., 175 in ground plan. Fig. &, 175 in vertical mid section 
transverse to the line of wall. The dotted lines, show it as 
it stood before the earthquake, the hard lines representing 
tne respective positions, in which I found the three blocks 
of stone lying, on the floor with the loose brick and plaster 
rabbish (chiefly) in the midst just as they had fallen ; and 
Photog. No. 183 represents their appearance, and that of 
the wall from which they had been separated. The three 
blocks of stone merely stood against^ the face of the chimney 
recess of the wall, and were made good to it with mortar, 
as was also the bit of pyramidal brickwork above the lintel. 
There was no bonded connection between them^ nor any 

x2 



V/e THE CAMIXE. 

real cohesion, as the smoked surfaces of the fitoes of junc- 
tion proved, that the expansion and contractioii of the 
limestone blocks by change of temperature (when fires 
had been lighted) had completely severed the mortar 
union between them and the walL 

The whole fabric stood^ therefore, ready to be overthrtnm 
bj any force competent simply to overset it upon its base, 
in a southerly direction. The Figs. 6, ^c., 175 show that 
the whole mass had canted over to the south, turning upon 
the front low^er arrises, of the side or jamb blocks, the latter 
carrying the lintel, for a short portion of the arc of descent^ 
upon their upper ends. The brickwork above, owing to 
the position of its centre of gravity with reference to its 
base upon the lintel, when freed from the face of the wall, 
and the small velocitv with which the mass must have been 
overturned, had fallen on the central space of floor, between 
the three stone blocks. The lintel block, had lauded upon 
tlie floor, close to the upper ends of the side jambs, and 
had then, partly by the direction of descent, partly by the 
effects of its own elasticity, and that of the beton and tile 
floor, either fallen over, or slided (or both), forward a few 
inches further south, having been broken in two by the 
stroke on the floor, at a soft joint in the limestone. The 
two side jambs, from their peculiar form in horizontal section, 
and their setting, at an oblique angle to the face of the wall, 
had canted round the imur angles of the front arrises at their 
bases ; and in their descent, the moment they got free from 
the lintel, had turned round partiall}^ upon an axis parallel 
each to its own length, and lay, after thus rotating through 
about 90"^ each, with its east face uppermost, both haviDg 
rotated towards the west ; so that when fallen, E was re- 



THE GAMINE. 309 

moved further west from the centre line of the " camine," 
and F in the same direction nearer to the same line. The 
centre of gravity of the whole lintel block, in the same way 
was posited, at a point a little to the westward, of the 
vertical plane normal to the face of the wall, and passing 
through it as it had stood erect. The inner face (or cove) 
of the lintel, was uppermost as it lay on the ground, proving 
that it had simply been thrown down, without any secondary 
disturbing force. 

Now this overthrow might have been produced either by 
shock from the south to the north acting upon the mass by 
its inertia, or by a projecting force, of a shock from north 
to south, carrying the wall along with it, forcing forward 
the chimney breast, and then at the return stroke, (or 
second half of the wave,) projecting it towards the south. 
Each assumption would lead to different results; but as 
there exists abundant and quite independent evidence that 
the general direction of wave movement at PoUa was one 
from north to south, and rwt the contrary, we must conclude 
that this " camine," was projected, and thrown by the 
forward stroke of the wave. The rotation of the side 
jambs, and the position of final deposit of the lintel, prove 
that the direction was somewhat, from the east of north to 
the west of south, and geometrical considerations based on 
careful measurements on the spot, prove the wave-path to 
have been 165° W. of north which produced the overthrow. 

Eeferring to Eq. IV., Part I., we can adopt the fall 
of the pieces of this *' camine," as a means to determine, 
both the angle of emergence, of the wave-path here, and the 
velocity of the wave particle at its maximum. 

The lintel G moving through a very small arc at the 



310 ANGLE OF EMERGENCE AND 

commencemeDt of its motion, may be assumed to have 
moved horizontally and free of restraint from the jamb 
stones. The height of its centre of gravity from the floor, 
was 4'33 feet ; but inasmuch as the small bit of pyramidal 
brickwork above it, was separated and began to move 
along with it, we may consider the centre of gravity of the 
lintel raised by it to 5 feet. The block was thrown from this 
height to a horizontal distance of 7*2 feet, including that of 
its having once turned over, towards the south upon its front 
arris on reaching the floor. 

We may further conclude, that as it so came to resty the 
velocity impressed^ at the first moment of its motion in an 
horizontal direction, was not greater than su^Hcient to make 
it overset upon that edge. 

The difference of the side and diagonal of the lintel (in 

transverse section) = 0*62 feet; f of this is = H, the 

height due to the horizontal velocity of overthrow. 

Then 

b = 5 feet . a = 7*2 feet, 

and 

— 6 = a tan e — -—pz 

4 H 

from which putting in the values we obtain 

Tan e = 1-472 

and e =-. 55' 49', the angle of emergence. 

But F^ = 2 y n, the horizontal velocity ; the total 

velocity, or that in the direction of the wave-patn is 

therefore, 

V^ = 2 ^ H . sec^ e 

whence 

V = i2-8i;3 feet per second. 



VELOCITY DETERMINED. 311 

If we apply this same method, to the jawh stones alone, 
or, as above, to the lintel alone, or to the whole viewed as 
a single mass, we arrive at the same value for Y, within 
extremely narrow limits. 

The assumption upon which this method depends (as 
respects the horizontal velocity impressed) is open to the 
objection of being slightly arbitrary ; whether by compen- 
sation of errors however, or not, the result arrived at is 
extremely near to the truth, as will appear further on, and 
is controlled by the following calculation, which is open to 
no such objection. 

Taking the overthrow of this " camine," in connection 
with that of the wall B, at the south end of the palazzo 
from which the upper part was thrown off. We have here 
two different bodies at the same spot, projected by the 
same shock, and by the same phase (the second) of the 
wave ; and we can apply the method developed in Part I. 
(Eq. XL. to XLVI.) to determine both the emergence of 
the wave-path, and the velocity of the wave particle, in that 
path. 

a and a\ h and V being the respective horizontal and 
vertical distances of projection, we have 



and 



whence 



- 6 = 


a tan 


e 


a^ 




4Hcos' 


e 


- A' = 


a' tan 


e 


a'^ 




4 H cos^ 


e 


Tan 


e — 


a^ 


B M B X. 








a a' [a' — a) 




nnrl H Oi 


rkQ^ /> - 




a a' (a' — 


a) 



4:(ab' - a' b) 



312 VELOCITY CONFIRMED. 

and substituting for H its value — 

if 

a a' (a' — a) 



F=^x 



2 cos* e (a b' — a! h) 
now we have for the " camine " 

a = 7*4 feet, at the final point of repose 
h = 4-33 feet 
and for the south end wall 

a' = 14 feet, 6' = 30 feet 
Therefore 

13-69 



- 4-33 = 7-4 tan ^ - 



-30 = 14 tan e - 



H cos* e 
49 



H cos* e 
solving we find 

Tan^ = 1-357 and ^ = 53° 37' 
and horizontal velocity F, = 8*03 feet per second and 

V = F, sec e = 13 '490 feet per second. 

The difference between the former calculation and this 
is = 0-G27 feet per second, or little more than half a foot 
per second. If we take the mean of the two determinations 
we find 

Y = 13-176 feet per second. 
There can be little doubt, that the small bit of brickwork 
imposed over the lintel block, of this '' camine," in moving 
at first, along with the lintel, and with a longer radius at 
the commencement of the trajectory, communicated to the 
lintel block, a velocity slightly greater, than alone it would 
have been projected with, and that hence the velocity 
deduced from the measurements of the axes of a audJ, 
may be slightly in excess. The true maximum velocity 



\ 



APPROXIMATE AMPLITUDE. 313 

of the wave here therefore, as deduced from three inde- 
pendent sources, all corroborating each other, must be close 
to 13 feet per second. 

A chimney hood of brickwork standing over the charcoal 
hearths in this kitchen, was at the end wall of nine inch brick- 
work A, (Fig. 185, Sketch Coll. Roy. Soc.) started out from 
the same line of wall, by about 2i inches at top, in a height 
of 1 2 feet, but was not overthrown. It was propped how- 
ever, by the return portion of the hood, at right angles to it, 
and so cannot be adopted for calculation, although affording 
a rude measure, that the velocity must have been small. 
In this same kitchen, the naked oak planking, of the ceiling 
or floor above, brown with wood smoke, shows where the 
ends of the boards have been draion from their insertions in 

the walls, in the direction of their own length, and therefore 
transverse to the north and south joists, upon which they 

were laid, but which have not been moved, but to which 

the planks were not spiked or trenailed. The mark of 

the white mortar, shows the draw or shove to have been 

from north to south ; it is 2|: inches at the west end, and 

4 inches at the east end, of the east and west wall, in a 

length of 25 feet; and as the normal to this wall bears 

10° E. of north, the horizontal direction of wave-path 

deducible from this is as before, about 165° W. of 

north. 

The actual amplitude of the wave in an horizontal 
direction cannot have greatly exceeded the average amount 
of shove, of these heavy bcton and plank floors, and hence 
cannot have much exceeded 3 or 4 inches here. 

In another room stands in a corner, against the wall T, 
which ranges north and south 10"" E., and abutting upon the 
wall S at its southern end, a very heavy oaken household 



314 VELOCITY AGAIN OTHERWISE OBTAINED. 

press (Fig. 184, Sketch, Coll. Roy. Soc.) It was 10 feet 
6 inches high, 9 feet 6 inches long, and 2 feet 2 inches wide 
from front to rear. It was not thrown down by any east 
or west movement, but was shoved, by a north and south 
movement, along the beton floor upon its eight stumpy 
oaken feet, each 4 inches square (surface of contact with 
the floor), in a direction towards the south. If inch from 
the north wall against which it abutted. 

The owner informed me, that it had been quite full of 
household articles, pretty uniformly distributed on its 
shelves ; that it had not been filled so as to be top-heavy, 
or unequally loaded ; and they estimated the total weight 
at about 800 rotuli = 1552 lbs. avoir. A quantity of china 
which occupied the upper third in height of its two southern 
divisions, was all found broken and thrown into a heap, at 
the south end of the shelves. A low velocity horizontally, 
not exceeding 2 feet per second, would have suflBced to 
make this press slide that distance upon a smooth floor, 
which would be only a little above 3i feet per second iu 
the wave-path. It must therefore have been arrested by 
some inequality in the floor, or by its feet ploughing into 
the beton, and will give no certain result, except that the 
velocity was suflBcient, to dash the contained china first north 
by the first phase, and then south by the second phase of 
the wave. 

In one of the great drawing-rooms there stands still in 
situ^ a very ponderous cabinet or chest of drawers of wabut 
(Fig. 186, Sketch Coll. Roy. Soc), with its back against a 
wall running east and west, and free to fall to the south. It 
was quite full in every part with house linen, and estimated 
to weigh 400 rotuli = 776 lbs. avoir, (cabinet and con- 
tents). It rests on four irregularly-shaped feet foniied by 



LIMITS OF ERROR FOR VELOCITY ASSIGNED. 315 

perforations in the fronts ends, and back, and was neither 
overthrown nor shoved out from the wall at back. 
Referring to the Equation Y., Part L, 

we have here = 33°, a = 4-75 feet, and b = 2-80 feet, 
as the mass must have fallen over, by rotating upon the 
most advanced angle at the base. Solving for F, therefore, 
we find the horizontal velocity necessary to have pro- 
duced overthrow to be 

F= 7-378 per second. 

but 6, the angle of emergence here, we have found to be 

65° 49' from the " camine," and V, the velocity in the path 

of the wave, is 

Y = F sec e, 
whence 

Y = 13-1328 feet per second. 

The velocity, Y, given by the '* camine," which tms over- 
thrown, is 12*863 feet per second by our first calculation ; 
that necessary to overthrow this cabinet, which was not 
overthrown, we find is 13-133. We have therefore obtained 
the true value for Y, within limit of the difference, or within 
0-270 feet per second of the total velocity — a possible 
error of less than 2i inches per second. 

The maximum velocity of the wave vibration at Polla 
may therefore be concluded with confidence to have been 
in round numbers 13 feet per second. The mean velocity 
obtained fi'om both calculations, 13*176 feet per second, is 
a little more (0*043 feet per second) than suflScient to have 
overturned this cabinet; but the slightest inequality in 
its loading, or in its parts, by altering the height of the 



316 FIRST INDICATIONS OF THE FOCUS. 

centre of gravity, would have sufficed to prevent its over- 
turn, unless by a velocity greater than that assigned, by 
more than the difference as above. 

Everything at Polla consentingly proved a wave-path 
of steep emergence, and from the north, or very nearly. 
The result, united with my observations in the upper part 
of the valley of the Tanagro, proved that the wave-path, 
as determined at Naples, either belonged to a separate 
focus altogether, or must have some complicated relation 
of disturbance, by reflection or otherwise, with the focus I 
was looking for, and which it now began to appear, I should 
find somewhere to the north, and not very far east or west 
of the meridian I was then upon. I therefore dismissed 
from my thoughts for the time the irreconcileable pheno- 
mena at Naples, leaving it to ftirther observation to solve 
the apparent enigma. 

The Judice of Polla, Signore Ferdinando Ganuzzi, po- 
litely accompanied me over the place. He had been at 
Polla on the night of the earthquake. According to his 
statement, confirmed by that of the Syndic, and others of 
the town, they were suddenly alarmed by the rushing 
sound, " Mormorio buccinante rapidamente ;" and almost 
instantly, while it vet was heard, the first great shock 
came — '* sussultatorio," succeeded in a very few seconds 
afterwards — how much they could not say, probably 
10" to 20" — by another movement, that some of them 
habitually spoke of as a second shock, which was " undu- 
latorio." But there was no such distinct interval of quiet, 
and arrival of a second shock, both being oscillatory, as was 
felt at Naples. The Syndic was on the second floor of 
his own houtje, which did not fall immediately; the first 



THE SOUNDS— THE TIME. 317 

moyement was sofiScient to caase him to lose his balance 
when standing, and to fall upon the floor. He found some 
diflBculty, owing to the second undulatory movement, in 
regaining his feet to fly from the shattered house. 

No correct observations were made as to the time of the 
shock : all was confusion and alarm. He noted his watch, 
and by it the time was 10^ 15" solar time, in Frankish 
hours. But he admits that all their watches and clocks are 
regulated by the setting sun, and are not reliable within 
narrow limits. 

There was a second shock of considerable violence about 
an hour after the preceding, which shook down many 
buildings, that had been shattered by the first. 

The Capo D'Urbano, a very intelligent man, made a 
curious and probably not unimportant remark, as to his 
experience of the sound. It seemed to him to reach him 
" through his legSj as he stood up," although, he added, 
" it was everywhere." This suggests the probability, that 
much of the sound in earthquakes may reach the auditory 
tierves, by transmitted vibration from tiie ground or other 
solid objects, through the bony skeleton ; just as when a 
poker held by a string to the ear is struck, and thus 
may convey from a very small vibration an overpowering 
sense of sound to the auditory nerves. 

I took from the centre of the middle arch of PoUa Bridge, 
several intersections to correct magnetic declination by. 

Monte Corticata bears . .170° W. of north. 

Tower of Diano (highest tower) 179° W. 

Atena (high tower) . . . 1 56° E. 

La Sala 152° E. 

Pizzo di Cirazzo . . . 1 79° E. 






318 IL VALLONE— MARGINAL TERRACES. 

These give a declination varying between 13° 30' and 
15° 30' west. I also took an observation of the sun, but 
on computing I fin(J that some decisive error must have 
occurred in my note of the sun's azimuth, which renders 
the observation valueless, as there was no ground for sup- 
posing any material disturbance of the ordinary amount 
of declination at this spot, more than at La Duchessa, 
where the same error appears to have been made. 

As I left PoUa in the afternoon, the grand plain of the 
Yallone di Diano opened before me, level almost as a sea^ 
of deep rich alluvial clays, which, as they approach the 
roots of the mountains that rise almost abruptly from the 
plain, assumes the form of a sort of sloping and almost 
continuous terrace all round the plain, elevated every- 
where a few feet above its average surface, seldom rising 
more than 40 feet above it, frequently not half that 

The outline section of this terrace, as it sweeps towards 
the centre of the plain, is that of a flat., hollow, parabola- 
like curve, with a slope varjing from 15 to 1 to 60 to 1, 
or even still more gradual, and suggests at once to the 
eye, the geologic conditions that produced the piano ; onc« 
a large lake, or arm of the sea, which found egress for its 
waters at a level probably not lower than the summite 
of the Campostrina Pass. In that condition of things, the 
rich bed of mud was deposited, that now forms the basis 
of the valley and of its agricultural wealth. 

The great fracture, through which the Galore now finds 
its course sub dio^ must have been subsequently formed, 
and through it the lake was drained down to the level o 
its marginal terrace. Its subsequent progress of desicca- 
tion must have l)een gradual, and dependent upon XhQ rate 



ITS FORMATION— SMALL SLOPE. 319 

of erosive deepening of the river at its north extremity ; 
and for ages it must have remained a shallow and pro- 
bably' pestilential lake, of above 20 miles in length and 
4 or 5 miles wide. The total difference of level now, 
between the water of the Calore at Polla and at the junc- 
tion of the Peglia with it at the extreme southern end, 
is said not to exceed 6 or 7 feet by Signor Palmieri of the 
Corps of Strade e Ponti, or only 3 inches to the mile. 
The marginal terrace round the plain contains numerous 
fragments of limestone, some angular, many more or less 
rounded. But the great clay central bed scarcely presents 
a pebble until high up towards the southern end of the 
valley, where the washings of the hill-side torrents disclose 
coarse gravel and boulders also, embedded in it. On the 
west side of the valley, I pass St. Arsenio and St. Pietro, 
both low-lying villages, placed upon the level of the marginal 
slope, that like a great shallow saucer, surrounds the plain. 
These towns have suffered but slightly, although not five 
miles in a right line from Polla, and St. Pietro, the more 
distant, has suffered the most. The damage done, how- 
ever, is almost confined to old houses, built of the usual 
sort of wretched, short, nobbly, bondless limestone rubble, 
of rounded lumps like irregular loaves, of from 6 to 
16 inches diameter, with thick joints, of bad mortar, made 
of clay rather than sand ; the general direction of wave- 
path from 142° to 144° W. of north. 

The character of the limestone of the mountains at both 
sides of the valley, begins rapidly to change, from that of the 
"valley of the Tanagro and Salaris. It is no longer the 
Iiard, sharply-fracturing, clearly-bedded, and well-defined 
stone of the latter, but a loose, irregular, ill-defined, and 



320 CHANGE IN THE LIMESTONE— LITHOLOGICAL CHARACTER. 

inarficulately-heMedy crumbly stuff, extremely like in 
lithological character, the white and yariegated limestone 
beds, of great portions of the upper limestone of Roscom- 
mon, Leitrim, and King's County, in Ireland, but much 
more sandy and siliceous. 

Such bedding as is traceable upon the surface, appears in 
a direction almost vertical, and although with many changes 
of strike, having, upon the whole, directions ranging trans- 
verse to the main axis of the Vallone ; and hence, upon 
the whole, presenting the flat of the bedding, to the direc- 
tion of the wave-path along the valley. There is no 
general indication of continuity of bedding or of formation, 
at the opposite sides of the valley, nor anything that 
decisively points out, whether this limestone of its flanks 
continues right across beneath its clay filling or not. It 
seems highly probable, from the general structure of the 
country, however, that it does so ; and equally so, that 
limestone, breccia, and marl beds, may lie between the 
crumbly limestone and the alluvial clays. The more dis- 
tant and higher summits, visible clearly by the telescope- 
particularly those on the east behind Atena — present more 
of the character of the hard limestone of the Tanagro. 
The limestone of the lateral hills is so ill compacted, and 
so easily acted on by air, water, and carbonic acid, that it 
is cavernous in every direction, and weathers into holes 
and pits of fantastic forms. In hand specimens, its struc- 
ture frequently shows it to consist of a mass of compacted 
crumbs, of rather harder limestone, angular, and not mucb 
unlike in size and form, Ycsuvian "lapilli," but ver2 
slightly coherent by a softer calcareous paste. 

This form, gmdually passes into an almost white cr 



ROAD FROM POLLA. 321 

taceous-looking limestone, very soft, friable, and filled with 
disseminated fine white sand, in many places, particularly 
along the east flank of the Yallone. The hill sides every- 
where present strong evidences of denudation, down to 
within three or four hundred feet of the level of the plain . 
Their summits and flanks are all swept almost bare, and 
the great deposits of detrital material above the plain, are 
only found in hollows, where it was entrapped, or in steep 
banks not elevated far above it, and now rapidly eroding 
by torrents. Almost all the scattered buildings that I pass 
along the plain, going southward, present indications of a 
general wave-path from north to south, varying some points 
east or west of that. On the east side of the great military 
road, however, about a mile from PoUa, are some isolated 
buildings, not more than 150 feet above the plain, yet upon 
the solid limestone, which present decided east and west 
characteristics of wave-path — one especially, a nearly new 
building, having a wall of about 50 feet in length running 
north and south, and connected with othei-s nowhere but at 
its extreme ends, by two transverse, or east and west walls. 
About 7 feet in height is thrown oflF the top of the north 
and south wall for its whole length, and thrown towards 
the west and south, while the east and west, or end walls, 
are merely fissured slightly. The original height of the 
fidlen wall was about 35 feet, its thickness 2 feet, and the 
mortar was not yet indurated. The debris had rolled down 
a slope of 1 in 6, and much of it was 20 feet from the base 
of the wall, and hence did not admit of any calculation as 
to angle of emergence. 

It was obvious that this was some local disturbance 
connected with the rocky range behind (to the east), but 



322 HEIGHT OF THE GREAT PLAIN ABOVE THE SEA. 

what I could not at the time discover. At about 2 miles 
south of Polla, and at a point of the road about the general 
level of the central plain here, I took by barometer the 
level of the Vallone. At 1^20 Greenwich - time (14th 
Feb.) barom. reads 29*6 inches, thermo. 62°, which, re- 
duced, gives 581 '5 feet for the level of the central plain 
above the sea. Either by misreading, or through some 
great inequality of atmospheric pressure on this day, be- 
tween Naples and the Vallone, this observation is cer- 
tainly about 100 feet below the truth; for the bed of the 
Tanagro at Auletta was ascertained to be 576 feet above 
the sea. The waters, issuing slowly from St. Michael's 
cavern, are about 80 feet above the river beneath, and 
there is probably 20 feet fall between Pertosa and Au- 
letta ; while it is probable that the fiill in the rocky tube 
is but a few inches between the water at Polla and its 
issue at the cavern. There must therefore be a fall be- 
tween Polla aud Auletta of about a hundred feet. We 
may therefore take the mean level of the Vallone di 
Diauo at about 700 feet above the sea, and the barrier of 
Campostrino, before its fracture, stood 1,3 G3 feet above 
the plain. This was the depth of the ancient lake or arm 
of the sea. 

While at Auletta, the gendarmes and others there, had 
affirmed that on the night of the earthquake, they had seen 
some unusual sort of light in the sky or air, and some of 
them said that it appeared to come up out of the earth. 
At the moment, I looked upon this as a superetitious tale; 
the rather, as Padre Mancini had not remarked it ; but I 
find almost every one I converse with in these districts, 
speaks of having seen some unusual halo-like light in the 



LUMINOUS PHENOMENA. 323 

sky, before and not long before, the shock. Many describe 
it at second hand, and these differ much in their statements 
as to time of its appearance, and give no intelligible 
accoont of its character; but many others say they saw 
it, and attempt to describe it as something like the light 
long after sunset, streaming up from the horizon at some 
one point, a sort of zodiacal light or phosphorescent dif- 
fused halo; whilst some point to one direction, some 
another, as its azimuth of apparition. Others — and 
amongst these were the gendarmes at PoUa — say that the 
light seemed to them to emanate from the earth itself; 
and those that were in the dark gloomy lanes of the 
towns before the shock, say that some sort of luminosity 
lighted them upon their way. 

Much, most of this, may be but the fancies of an ima- 
ginative and wonder-loving people ; but in a country where 
communication is so bad, and news travels so slowly, it 
would be remarkable if so widely-diffused a notion, and one 
without any obvious popular basis of suggestion, should be 
devoid of all foundation in fact. I have therefore recorded 
it; and before dismissing the subject I may add, that I 
found the same story prevalent in the valley of Viggiano 
also, but lost all trace of it farther south, east, or north^ 
while to the westward I heard the first of it at Auletta. 
It therefore has this remarkable attendant circumstance 
that, if febulous, the fable was confined to an oval district 
around the most disturbed region. Conjectures would be 
useless as to its nature, but future observation directed to 
the point, may determine whether some sort of auroral 
light may emanate from the vast depths of rock formation, 
under the enormous tensions and compressions, that must 

y2 



324 POSSIBLE NATURE OF THE LIGHT. 

precede the final crash and rupture that produces the 
shock, or whether volcanic action going on in the unseen 
depths below may give rise to powerful disturbances of 
electric equilibrium, and hence to the development of light ; 
just as from volcanic mountains in eruption lightnings con- 
tinually flash, from the huge volumes of steam and floating 
ashes above the crater. 

Atena, which in Pliny's time gave its name to the 
whole valley (campi Atenati), is a town of extreme 
antiquity, its name indicating its Greek foundation. It is 
situated upon the east side of the great valley, and stands 
upon the crest, of a spur of absolutely bare rock, jutting 
from the lateral range, and having a small transverse 
valley or gorge to the north of it. The slope or angle of 
emergence of the rock, to the north of the town, from 
beneath the deep alluvium is about 30° with the horizon 
at a (Fig. 187) ; the bedding ill-defined but apparently 
with a general east and west strike and steep dip. 

Don Vincenzio Jaehetti, an inhabitant, an intelligent 
man, who had been appointed a Deputy Sotto Intendente 
since the earthquake, accompanied me over the town, which 
has sufi^ered terribly ; its streets, especially upon the north 
and south sides, arc choked with rubbish of fallen build- 
ings to a depth of 10 or 15 feet above the former level, and 
encumbered with fmctured and entangled beams and joists. 

The Photog. No. 189 (Coll. Eoy. Soc.) shows the east end 
of the cathedral church, and various adjoining buildings, 
looking nearly westward. The general evidence of the 
w^ave-path with steep emergence from the north, is ob- 
servable in the thrown and shattered north and south walls, 
and in the wedge-like mass, projected from the S. E. quoin of 



ATENA AND ITS NEIGHBOURHOOD. 325 

the chancel, and the roof of it and of the south transept fallen 
inwards. The horizontal direction of wave-path deduced 
from the thrown quoin, and from the average of five sets 
of fissures in the church, was 165° 30' E. of north, and the 
angle of emergence 47° 30'. The angle of emergence 
given by thrown quoins in three other buildings (dwelling- 
houses), of much worse masonry, however, and therefore 
capable of less exact determination, was only 39° 30'. 
Lower down upon the eastern slope of the town a large 
heavily built range of building, with front walls to the 
narrow street 3i feet in thickness, running nearly east and 
west, shows fissures of two inches wide, on the level of the 
first floor above ground, which indicate a wave-path not far 
from north and south, 177° 50' E., the nearest approximation. 
One of these in the soffit of the arch, over a *' portone " 
leading to a " vicinello " is shown in Sketch Fig. 190, and 
gave a path exactly north to south. A wall of old and little 
coherent masonry, has had six feet in height of its upper 
part thrown oflF, parting horizontally along, at 38 feet from 
the base. The mass of material has fallen at an average 
distance of 20 feet from the base, towards the south, and a 
point or two towards the west. The angle of emergence 
deduced from this (the horizontal velocity as at PoUa) is 
between 45° and 50°, dependent upon the constant adopted 
for the adherence of the mortar and masonry at the base 
of separation. The result sufficiently corroborates those 
above given from more certain data. 

The diflference of effect of the same shock, upon well and 
ill-constructed buildings, is forcibly shown here. The 
square campanile of the church stands nearly isolated, its 
north and south side walls being nearly parallel with the axial 



326 ANCIENT CHARNEL-HOUSE. 

line of the cathedral ; the east and west walls stand 120** 
west of north. It is about 9 feet in height ind 22 feet square 
at the base. The walls, 3 feet 8 inches thick at bottom, 
and only 12 inches at the summit (Photog. No. 188 J and 
Fig. 180) are very well built, with large, long-bedded, 
heavy ashlar quoin stones, 3 to 4 feet bed along the fieice and 
16 to 24 inches deep; cut limestone jamb linings and string 
courses ; and the filling in between these, well-laid coursed 
rubble. At each of two points of its height — viz. the fiist 
and second string courses — the walls are connected by four 
slender chain bars of 1| in. x f in. iron, with transverse 
cotters outside the wall &ces. This has stood uninjured, 
without even a crack, in the midst of surrounding ruin, a 
clear proof of what sound and good building would do, in 
securing the safety of the inhabitants of the towns, in 
earthquake countries. High up upon the rocky hill side 
above the town also, are many summer lodges {scaffce) 
which are very well built, and of recent date ; and although 
prol)ably a thousand feet above the town level, they have 
suffered very little : they are chiefly buildings of a single 
story, and owe their safety to this and to their good con- 
struction. 

A large portion of the ancient walls of the town remain, 
probably of mediaeval construction. At one part of these a 
large cylindrical tower existed, which for ages had been 
used as a cemetery. From the side of this, overhanging the 
precipitous face of the hill, a large mass had been thrown, 
and had exposed to view, the surface of a solid cylinder of 
human bones, of several feet in depth, those at the bottom 
reduced almost to crumbled bone-earth, while those on the 
surface at top, were still perfect, and some not quite 



FISSURES AT THE GALORE. 327 

lenuded of ligaments; a proof how ancient in Southern 
[taly this barbarous mode of naked interment of the poor, 
[which is still in use at Naples) has been. The chief 
nterest to science, however, lay in this; many of the 
)ones and some skulls had been thrown from the mass 
Jong with the debris of the wall; upon the precipitous 
imestone slope where they rested, some small calcareous 
iprings oozed out, and their deposited tufa was visible, 
t is not improbable that these human bones may become 
ncased in tufa, and the latter may hereafter form at this 
pot a coarse conglomerate, with the fallen masonry and 
imbedded bones. 

The position of the tower is imperfectly seen in Photog. 
i^To. 191 (Coll. Eoy. Soc.), and its appearance in Sketch 
^ig. 192 (Coll. Roy. Soc.) : the tower was about 28 feet in 
Qtemal diameter. 

The time of the first great shock was marked here by 
he stoppage of the communal clock at 10** 15" Italian 
ime reduced to Frankish, but no exact reliance can be 
daced upon this. Signor Jachetti admits that all their 
locks and watches about the country are either set by 
undown or by the watches of travellers coming from 
Naples or elsewhere. 

Upon the bank of the Galore, out in the centre of the 
lain opposite Atena, Jachetti pointed out to me, a fissure 
1 the deep clay soil, which had been opened nearly parallel 
y the stream. It was simply a land-slip of a few hundred 
jet in length, the fissure 6 or 7 inches wide, and the 
ertical descent about the same, and originated at the 
iolent shake at the shock. 

Immediately behind the town, in the small lateral valley, 



328 FISSURE ABOVE ATENA. 

a fissure also exists io the earth, which Signer Jachctti 
affirms when first opened este[i<led into the rock beaeath, 
but that the rains have since filled the latter in. I have 
much doubt of the fact, however, from his description of 
the appearance of the rock at the alleged fissure, which 
rather seems to have been an ill-defined junction of bedding 
at a steep angle, and that the outer bed of rock had slipped 
a little downward and outwards, over and from that on 
which it reposed. The earth fissure, however, was 
traceable for several hundred yards beyond the saddle- 
back of a colline, connecting the spur of Atena with the 
main range of lower hills behind. It appeared originally 
to have been about 2 or 2i inches wide, and one side 
bad descended about 3 inches below its original posi- 
tion. It was in earth over the limestone, varying from 
2 to 4 feet in depth — a manifest case, like that in 
the pUiin, of slippage and shaking off of loose material, 
and not of actual fracture by bending or dislocation 
(Fig. 103). 




A second small gorge, with deep and precipitous sides, 
runs in an east and west direction behind Atena, and falls 



TOWN OP DIANO— VALLONE DEL RACCIO. 329 

of crumbly limestone rock have taken place, from both its 
&ces^ but chiefly from that on the south side, where the de- 
tached masses have fallen from the ends of nearly vertical 
ill-defined beds, whose strike is N. W. and S. E. This, 
like every case of fallen rock that I have so far observed, 
has been detached from a vertical or nearly vertical bed, 
where, owing either to the joints of the beds themselves or 
to cross fissures, there was little or no adherent connection 
with the adjacent rock ; in fact, cases of loss of equilibrium 
and fall by inertia, and not of rending asunder through 
the solid stone, and dislocation by the direct energy of the 
shock. 

Upon the opposite or west flank of the Yallone, and 
further south, stands Diano, the town from which it takes 
its name, upon a low, stumpy, jutting-out spur, of soft 
limestone, to the eastward of the great range (see Photog. 
page 165, No. 108, Part I). 

The main direction of this spur, is nearly due north and 
south by compass, rising gradually from the plain at the 
north end ; and it is completely cut oflf from contact with 
the great lateral chain of mountain, except at nearly the 
level of the plain, by the long lateral Vallone del Eaccio, 
which brings in one of the great feeders to the Galore on 
its left bank, and whose bed in the bottom of the vallone, 
seems to lie in the line of a great dislocation. 

This town has suffered comparatively little by the shock, 
many fissures, and a few of the old ill-built miserable 
class of houses thrown down, direction apparently north to 
south, none affording good data. 

The beds of limestone rock at both sides of the valley, 
from above Atena southward to below Diano on the west, 



S80 nacuNmr or diano vxshknajy. 

and Ia Sala on the east, are vertical or nearly vertical 
(so for as bedding can be discerned at all), taA Hie line of 
strike is nearly east and west 

The comparative immnnity from destmction of DIano, is 
not difBcnlt to explain. The direction of wave-path was hen 
nearly dae north to soath. It therefore passed frmn tiie deep 
clays of the piano into the long spur cnr colline of tlie town, 
end on, (see Sketch No& 194, 195,) losing a large portuui of 




its vis vivd at the janction, and a still lai^r porticm, 
in passing through the great nnmber of nearly verfjcal 
beds of limestone, about a mile in total thickness, before 
reaching the town, in a direction perpendicular almost' to 
their planes, like a bullet shot through the leaves of a 
thick book. 

Again, the shock transmitted southwards through the 
lengthway of the great flanking chain to the westward, was 
almost completely cut of from reaching Diano at all, by the 
Tallone del Raccio to the north and N. W. of the town, npon 



ST. ARSENIO—TORRE— ST. RUFO. 331 

the S,W. side of which, on the steep slope of Monte 
Mottola, the eflfects of the partial extinction of the wave at 
its sur&ce as "a free or outlying stratum " were visible 
in considerable fialls of projected rock (loose masses chiefly). 
Nothing of the wave passing along the flanking range 
reached the town, therefore, but secondary waves of re- 
fraction and dispersion, coming up from beneath the town, 
as the residue of the unextinguished original wave passed 
southwards. 

Few better examples may be found, of the important 
effects of local condition, as modifying the effects of shock, 
or of the care necessary to observe and disentangle the 
phenomena. Of towns situated within three or four miles of 
each other, one is found almost totally destroyed, the other 
is scarcely injured. It seems inexplicable at first sight, 
that both should have been almost equally near, to the 
same subverting agency from beneath; yet nothing is 
simpler or more certain when explained, than the con- 
ditions which shielded the one, and left the other exposed 
to destruction. 

The protectiDg circumstances as respects Diano will 
be understood by comparing Sketch No. 194 with the 
Section Sketch No. 195, supposing the line a 6 to be that 
of the wave-path. 

St. Arsenic, Torre, and St. Pietro, small places on the 
west of the Vallone Diano, but north of Diano town, were also 
more or less protected by similar conditions ; cut off from 
the great flank range, by the little lateral valley of the 
Aqua del Secchio, and others. They suffered much more 
Hbsax Diano, however, and St. Eufo, on the south flank of 
the lateral Valley del Torno, still more than either. The 



332 MOUNTAIN REGIONS FAR WESTWARD. 

wave-path at St. Arsenio and St. Pietro was, from fissures, 
142° to 144° W. of north. 

Much further away to the westward, (10 to 15 miles west 
of Diano,) in the heart of the mountains, and in the great 
extent of rugged country, south of the very high table land of 
Piano di Salvagnuola, and still more south, in the valleys 
of the rivers Carmignano, Galore, (another west of the river 
of the Vallone Diano,) Pietra, and Cilnio, the earth-wave 
must have been propagated with much violence, but with 
frequent and rapid changes of direction, and hence rapid 
loss of vis mvd and speedy extinction. Castelluccia, Ottati, 
Corbeto, Laurino, and some other towns were greatly 
damaged. But there are vast tracts of uninhabited 
mountain and valley about here, and little is known of 
the shock in these, which I was unable to enter, as they 
were all under snow of considerable depth. 

Still further west, however, after the confluence of the 
above-named rivers which divide the country for above 
twenty-five miles in a nearly north and south direction (by 
compass), though in an irregular line, and previous to the 
approach of this river to the Bosco Persano, before its 
junction with the Salaris, the long valley of the western 
Galore arrested almost completely the violence of the 
shock, so that between it and the Sea at Paestum little 
of it was experienced. 

Returning to the Valley of Diano, upon a new piece of 
the military road not yet used, between Atena and La 
Sala, was a newly erected culvert, of three semicircular 
arches of 12 feet span, passing a torrent under the road, the 
piers, al)out 8 feet to the springing, all built of good 
squared ashlar, the arches turned in brick, tw^o bricks thick. 



CHANGED CHARACTERS OF THE LIMESTONE. 333 

The structure was not overloaded with material and was 
well put together, and the mortar still green. It did not 
exhibit a trace of injury. (See Fig. 196.) 




As I pass southwards, still in the valley, and approach 
La Sala, the mountain peaks to the rear and above the 
first low range of the east flank, all show evidence of 
increased looseness and softness of the limestone rock ; 
its bedding becomes more and more indefinite, its minute 
stracture, more and more like a mass of fine angular 
compacted fragments, of a rather harder and originally 
more aniform liasslc-looking rock, and its litholc^ical 
diaracter one of increasing chalky whiteness, with more 
and more silex intermixed, in the state of a very fine 
gritty white sand. 

The forms of all -the mountains behind, the rounded 
culmination of their summits, the curves of their flanks, 
with the flowing lines of the ravines, and swelling protu- 
berances of the hill-sides, all alike indicate, a very soft and 
easily denuded or weathered rock ; one of low elasticity 
and density, and capable of transmitting impulse, much less 
powerfully, and to a much less distance, than the limestone 
I had already encountered, and which with its maximum 



334 ROAD TO LA SALA. 

hardness and sonoricity I had foond in the flanking peaks 
of the Valley of the Tanagro, some twenty miles to the 
north. 

Many isolated houses and other buildings about here, 
founded upon the deep clays of the piano, exhibit by their 
fissures, an almost completely uniform direction of wave- 
path north to south, and an angle of emergence so small as 
to seem almost zero. I observe, however, that wherever 
such buildings are founded upon the limestone rock, upon 
the gentle slopes, of the lowest hill sides of the east 
side, of the Vallone, the wave-path tends a little to the 
E. of north, i. e. it seems to come from the line of the eastern 
flank range, more or less, but still with the prevailing 
north to south path ; the divergence towards a N. E. to S. W. 
direction being from 10° to 25° : and the angle of emer- 
gence, at once changes from nearly zero, to a pretty large 
one, but which gradually decreases as I travel south. 

Within a mile of La Sala, on the left of the road, stood 
a square, strong-built house, which was perfectly cardinal, 
and aflbrded excellent measurements by fissures and thrown 
wedges. It gave a subnormal wave-path nearly 171° W. 
of north, and an angle of emergence of 24°. Another ca^ 
diual building to the right of the road just entering La 
Sala, shows a subabnormal wave-path 155"^ W. of north, 
and with nearly the preceding angle of emergence, the 
wave here again appearing to come from the line of the 
lateral range to the eastward. 

Nearly opposite the town, I observe at a quarter of a 
mile out in the plain, several large haystacks (Fig. No. 197, 
Sketches Coll. Roy. Soc.) leaning over at top very much 
to the southward. They had their longer axes nearly 



LA SALA. 335 

east and west, and all were thrown to the sonth, without 
any twist. The people about, said they had been all built 
plumb, and were so, before the shock, an interesting proof, 
that a very light body may be overturned by shock, 
equally with one of great density, the inertia of motion 
being exactly proportionate to the weight. 

La Sala. — This town, although of Roman, if not of still 
earlier origin, and showing remains of much antiquity 
about the old Castello, seen above the town, is nearly all 
now of modem building ; and upon the whole far better built, 
than any town I have yet seen in the Vallone. It extends 
for nearly a mile and a quarter, along the slope of the hill- 
side, the buildings rising above each other, and present- 
ing very generally their greatest length in north and south 
directions, or parallel to the hill-side, which is nearly 
continuous, and unbroken by any deep lateral gorges, all 
along the east side of the Yallone. Not a single stream of 
any magnitude falls into the Galore from this, but all its 
feeders from the other or western side. This town is the 
seat of government of the province, and contains many 
large official and other structures. All are more or less 
fissnrod, but the iactually demolished buildings are few. 
This seems to have arisen less from diminished energy of 
the shock here, than from the substantial character of the 
buildings, and from the fact, that almost all of them 
presented their long dimensions to the line of shock, as 
may be seen in Photog. No. 198 (Coll. Roy. Soc.) of the 
town looking from the N.W. The general position of 
the buildings in plan, as they wound along the hill-side, 
is along a curve, as in Fig. 199 (Sketch, Coll. Roy. 
Soc.). There is an elevated little valley, at the back or 



336 HOUSE OP THE SOTTO INTENDENTE. 

east of the town, between it and the ridge of the Costa della 
Madonna, of arid limestone, and slender covering of soil 
at various points, but no fissures or falls of rock were 
visible. 

I found the Sotto Intendente, II. Cavalieri Gul®. Calvoso, 
living with the Signora in a comfortable wooden "barrac'' 
or hut beneath the town ; for although the great shock threw 
down so few buildings here, the alarm of subsequent minor 
ones, has caused those who could, for the present to desert 
their permanent stone houses. He accompanied me with 
his secretary, II. Caval. Ferdinando Lansalone, throng 
the town, and through his own palazzo (the Casa Officiate), 
which, though shaken and fissured, was still standing, just as 
it had been fled from by eveiy living being, on the night (rf 
the 1 6th December ; and as it had been locked up ever 
since, the pictures and many other objects within the 
house, were lying strewed or thrown about, exactly in the 
positions in which the shock had left them. The Sotto In- 
tendente gave me on the spot, and in the rooms, a very 
graphic and intelligent account of his observations as to 
what had occurred. 

There is no record as to the precise time of the shock. 
The clock at the Casa Communale was thrown down and 
stopped, but the hour could not be got from it, and its 
inaccuracy was admitted to be as great as usual. 

The house of the Sotto Intendente is founded on the solid 
limestone rock : it is a long and rather narrow two-story 
building of large size, stone built, with timber and tiled 
floors and roof, and well constructed. There are a few small 
fissures in the walls, indicating a north to south wave-path, 
emergent 20"" to SO"", but the latter evidence is uncertain. 



INTENDENZIA AT LA SALA. 337 

The long axis of the house, has a direction 20° W. of 
north. The room occupied by the Sotto Intendente with his 
&mil7 on the 16th December, is a nearly square one, on 
the first floor (i. e.^ one over the ground floor). They had 
not gone to rest, and he was first alarmed by a short, sharp 
rattling, with a jumping vertical movement of about half an 
inch, of a large white metal chocolati^re, that stood upon a 
marble-topped table at a, touching both the south and west 
walls. At the same instant he heard the " Rombo," which 
continued during the entire time of the shock. It was not 
very loud, but very terrible, and "seemed to make the 
floor and the whole house to tremble " — a hoarse and grating 
rumble. Before he could have reckoned twenty he thought, 
the great shock came, a distinct undulation, which several 
times swayed everything back and forwards, and lifted 
up and dropped down simultaneously, the horizontal move- 
ment having by much the greater range. 

As far as he could judge by his own perceptions, the 
range of horizontal motion did not exceed half a palm 
(3 or 4 inches). The movements did not instantly cease, 
after these great oscillations, the total number of which he 
could not be certain of — he thought they did not exceed four 
or six — but all was quiet after (as he supposed) about half 
a minute, when they all rushed out of the house. He 
never himself, lost his presence of mind ; on the contrary, 
he said that the minutest circumstances of movement, &c., 
that occurred in the room, from the instant when the choco- 
lati6re began to give tongue, seemed to stereotype them- 
selves, upon his observation and memory. 

A number of glazed lithographs, in flat wood frames, each 
hung from a single nail, upon the north and east walls of 

VOL. I. z 



338 PICTURES AND 

the room, A and B (Fig. 200). Within a second or two 
after the chocolatiere had begun to jump and make a noise, 

the lithographs hanging upon the 
wall A, began to oscillate slightly 
in the plane of the wall, or firom 
east to west, and the reverse; 
and at the same instant, those 
hanging upon the wall B, began 

Corrvdor, 

to oscillate slightly, out fix)m and 



:f?^^'?>^i:\i^ 




back to that walL i. e.. in the 

Fig. 200. ^ ' 

same east to west direction. The 
great shock now arrived, and the frames upon the wall B, at 
once began to sway forward and back in the plane of the 
wall, or in a direction south to north, and the reverse ; while 
those upon the wall A, commenced the movement out from 
and back to the wall ; and for a moment or two he thought 
they all moved more or less both ways, viz., in the planes 
and at right angles to the planes, of both the east and west 
and north and south walls. The motion ended finally, by 
the prints on the wall B, alone oscillating gently in its 
plane, with a decreasing motion, for two or three seconds, 
and finally coming to rest. 

Of the lithographs upon the wall A, the Sotto Intendente 
pointed out to me one, the dimensions of which (they were 
all quite similar) are given in Fig. 201, and he caused 
it to vibrate in both w^ays by his hand, as nearly as he 
could to the same extent, that he had observed it to have 
moved at the most violent period of the shock. The chord 
of the arc of vibration, in plane of the wall (east and west) 
was about 2 inches, and the semichord of the corresponding 
vibration, from and back to the wall B, was about 1*25 



PENDULE. 



339 



inch. The chord of vibration of the frames on the wall B 
in plane of that wall (or north and south), was 7-50 inches, 



IC-^ 



a 





Fig. 201. 

and the semichord corresponding from and back to this wall 
A, was about 4 inches. 

It was obvious, therefore, that here two wave-paths almost 
coincident in time had crossed each other, at a sharp angle, 
the one arriving first, being transmitted with more or less 
of an east and west direction, from the north and south 
axis of the great range of mountains to the eastward, and 
having an horizontal amplitude not exceeding 2 inches ; the 
other, which almost instantly followed, having a north to 
south direction, and an horizontal amplitude of 6 or 7 inches. 

Nothing observed, except the chocolati^re, gave any 
approximation to the extent of vertical movement or 
altitude of the wave which appeared by it, about half an 
inch at most 

Upon rushing out of the house. Signer Calvoso said, 
he was struck with the quietude of the night, and the 
general serenity of the sky for the season. The night 
was not a dark one, but he had observed nothing himself, 
of any unusual luminous appearance ; of having remarked 
which, however, numbers of persons had spoken to him 
since the 'shock. He however stated that having on the 

z 2 



340 THE SOTTO INTENDENTE. 

instant, to attend to many official calls, as well as domestic 
ones, incident to the alarm of all around, he might not 
have remarked any such phenomena, outside the house. 

In his "salone," or drawing-room, a large clumsy pendule 
in an irregular hexagonal frame, with the dial of about 
10 inches diameter, in the centre, like a picture, hung upon 
the wall parallel with B, in last Figure {i. e.^ in a plane 
20° W. of north), by a single nail and ring at top. A nail 
driven into the wall at N. (Fig. 202) was in contact with the 
frame, when the whole hung plumb, and prevented all move- 
ment of oscillation towards the S., but it was free to oscillate 
in the opposite direction, the nail corresponding to N. having 
been withdrawn from some cause. I found this pendule 
remaining out of plumb, and thrown to the northward, as 
shown by the dotted line (Fig. 202), so that the edge of the 
frame had moved 1*75 inch, from the nail at N. The 
centre of gravity of the whole, I found by trial, was in the 
centre of vertical figure, and the weight of the whole was 
8^ rotuli = 16*49 lbs., the frame projecting 5^ inches 
from face of wall. By trial I also found, that the friction 
of the back against the wall, required a force of 1^ rotuli 
= 2-91 lbs. to set it in motion from rest. Had it been 
free of the nail at N., it of course would have vibrated 
through an arc of 3 '50 inches, assuming each semiphase 
of the wave to have equal velocity, and neglecting the 
effect of emergence. 

From the considerable weight of the pendulum and the 
large proportion the friction bears to the weight (nearly 
1:5), it forms by its range of motion an approximate 
measure of the amplitude of the wave here in an horizontal 
direction — one too inexact, it is true, to found anv calcn- 



HIS SECRETARY. 341 

lation upon, but yet enough to convey a distinct notion of 
the extent of movement of a powerful earthquake shock. 

The actual lateral movement here was probably about 
3i to 4 inches — a range of motion which, made with a 
velocity as great, as that with which one reaches the 
ground, on leaping down from a height of 2i feet, may 
enable on^ easily to understand how readily persons are 
thrown down when* exposed to it. 

The Secretary Lansalone pointed out to me in his house 
two brass table lamps, fashioned as in Fig. 203, which 
stood upon a semicircular table, placed 
with its diametral side, in contact with 
a wall running 37° W. of north, the 
lamps being placed so that the line . 

X y was at right angles to the plane ^ac^f^^krm^ 

of the wall. The centre of gravity 

of either lamp, is 7 inches above the 

base, and the centre of oscillation is 

about 10 inches above the edge of the 

base, considered as centre of motion. The weight by trial 

= 1 rotulo 2 unci. 

At the shock one of these lamps was thrown off the table 
towards the north and the other towards the south, and lay 
upon the floor in the positions shown in Photog. No. 206, 
(Coll. Eoy. Soc), and Fig. 204. The china things upon the 
same table remained as seen by me, nearly undisturbed : 
they were low and broad based. 

The legs of the table were somewhat elastic, and as they 
sprung under the shove from the wall, in contact with it, 
no deduction as to wave velocity can be made from these 
lamps. Making some allowance for the effects of this 
elasticity, in giving divergence to the direction of throw, 




342 



THE SECRETARY'S TABLE AND LAMPS. 



uormal to the face of the wall, the position of the lamps 
indicates a wave-path, about 157° W. of north. 




Fig. 204. 

There are many pictures in this house in rooms unused, 
hanging from single nails, which have been caused to swing 
in the plane of their respective walls. Many remain, just 
as left by the shock, and all tend to show a general north 
to south direction, with more or less of movement from a 
diagonal line approaching east to west. Their friction was 
too great against the rough walls, to admit of further 
deduction. 

The Sotto Intendente, who, though a keen observer and 
very intelligent, knows nothing of science or of earthquake 
speculations, remarks to me that he has observed the build- 
ings situated on the harder limestone, everywhere in his 
province, much more shaken and injured,* than those posited 
upon the softer chalky stuff found here and further south. 

The church of La Sala, like numbers of others in Southern 
Italy, has been built, not in accordance with ecclesiologieal 
notions, but to suit the lie of the ground. Its axial line 
is 20"" W. of north, and it has a campanile, rectangular in 
plan, external to one flank wall, as in diagram Fig. 206. 
The upper part of this, previous to the earthquake, carried 
two bells, hung between the jambs of piers and arches on 
top. These were overthrown, down to the level of c c by 



CHURCH OP LA 3ALA. 




344 FALL OF THE CHURCH TOWEll. 

the shock, and the tower has since been taken down, to the 
level of the centre of the mock clock dial. By careful 
measurements of the standing portion, and by comparison 
of the taken down pieces, with the sketches and description 
of the Sotto Intendente, I was able to restore the design of 
the superstructure, and obtain a close approximation to its 
original height. Both bells oscillated in a plane, parallel to 
the axial line of the church. At the shock, whose wave- 
path passed obliquely through the open arches on the 
summit of the campanile, the jambs or side piers separated 
enough from each other, to permit the bells to be released 
from their pintles, and these were thrown to the ground, 
in the direction shown in Fig. 206. The larger bell 
remained unbroken, having fallen amidst some rubbish on 
the ground ; the smaller was destroyed, having descended 
from a greater height and fallen on hard ground. The 
piers did not come down at once with the bells, but fell 
shortly after. The place where the smaller bell struck the 
ground, could not be ascertained with certainty, but the 
Padre, the Sotto Intendente, and others, were agreed upon, 
and pointed out precisely, the spot where the large bell had 
alighted ; and its path of descent was also indicated by the 
breaches, which it had made in falling, in the eave tiles of 
the roof, and in those of a string course of the external 
flank wall of the church, near the campanile. The bell itself 
had been removed into the church (but the fallen rubbish 
was still on the ground) : it is very antique and remark- 
able for its form, and is correctly sketched in Fig. 206, 
No. 2. It bears an inscription in Lombardic (?) characters, 
and a date which I presume to be 1324 or 1336. The 
Padre, wlio is accustomed to judge of the weight of bells, 



THE ANCIENT BELLS. 346 

estimates it at 7 cantari = 1225 lbs., which agrees with 
my calcalatioDs from volume. 

The appearance of the church and tower is shown in 
Photog. No. 207 (Coll. Roy. Soc.), as seen from the N.W. 
Nothing can be inferred from the fall of this bell as to the 
direction of the wave-path (which we have already got from 
other data), inasmuch as it was obvious that a line drawn 
from the centre of the tower to the centre of gravity of the 
bell, at its place upon the ground at ^, would be far from re- 
presenting truly the plane in which its trajectory of descent 
had been made. It had first descended to n, and coming in 
contact with the eave tiles, had then taken a new course, 
and been thrown directly outwards or westward from the 
wall, in its further descent. 

It was also observable from the scratches, &c., on the 
bell, that the eastern pintle had given way first, so that the 
full force of the shock had not acted in projecting it. The 
shock acting at the centre of gravity s (No. 2), and the 
resistance of the last held pintle jt?, had caused the bell to 
rotate slightly before falling, and given it along with its 
glancing ofiF the eave tiles, a much more westerly direction 
of descent, than was due to the direction of wave-path 
alone. Both these extraneous forces also had reduced the 
horizontal distance to which it would have been thrown, 
had it freely pitched to the ground in its original path — 
both pintles being freed together. 

Taking the vertical height of fall to be that from the 
centre of gravity of the bell as it hung, to the level of the 
eave tiles, and the breach therein as marking the horizontal 
distance thrown, and applying the equation — 



346 ANGLE OF EMERGENCE INFERRED. 

we have 6 = 26 feet, and a = 16 feet as measured. We 
must estimate the deficiency of a fix)m the above circam- 
stances, and, adding ^, assome a = 17 feet 

Taking the velocity of the wave as we found it at Polla 
= 13 feet per second, 

H = — = 2-62, the height due to V, 

and solving for e — we have 



Tan e = 5'24 + v^299'9 - 289 ^ ^.g^^ 

and e = 27° 10' 

which is the angle of emergence, as given by the projectioa 
of this bell. This, owing to the disturbing conditions, can 
only be considered as approximatively trae, to within ± 
or 3°. The result, however, is corroborated by the same 
angle having been obtained otherwise, as already given : 
better data were not procurable at La Sala. 

The base of the church tower may be viewed as about 
the mean level of La Sala. The barom. reads 27*86 in. 
Thermo. 54^ at 11^ 0'. a.m. Naples time, 15th February, 
which reduced gives the altitude of the spot = 1768*30 
feet above the sea, and about 1000 feet above the piano at 
its northern extremity. 

The cause of the disturbances in the general direction 
of wave-path observable at various points since leaving the 
north end of the valley, began now to be apparent^ on 
examining with the maps, the relations of the lateral chains 
at either side, to the main direction of shock hereabouts. 

Referring to Fig. 208, in which is sketched the general 
form of the piano, and the prevailing lines of ridge, or 
summits of th(^ mountain mnges around it are marked bv 



WAVE PATH PERTURBATIONS HERB. 



k lines ; the main direction of the wave-path &om 
Dpostrina southwards is indicated by the large arrows 
w, wid is that given generally by everything in the 
ao, aoath of Polla, 
Padula. Bot on the 
t side of tiie valley, 
ig soathward, it is 
stantly disturbed by 

intermixture of ano- 

r wave-path oblique 

lie former, and with 

leasing obliquity the 

iier we go south; 

t intersecting angle, 

Qg small at Atena, 

Bter at La Sala, and 

ater still at Padula, 

i the direction of 

7e transit of this 

jndary shock being 

ays from N.E. to 

v., or from the lateral 

in to the east of the 

ley. 

t is obvious that the impulse given at the north end of the 

ley in a north to south direction, simultaneously to the 

p clays of the piano, and to the eastern mountain range 

ts north end, was transmitted comparatively undisturbed 

to direction through the former ; but, in passing along 

lateral ridge of limestone mountain across all the nearly 
tical beds, transverse vibration was produced along 




348 PERTURBATIONS EXPLAINED. 

the whole line of mountain crest, which oscillated trans- 
versely, like a thin plate or musical string, struck at one 
point, giving rise to a secondary wave whose path was that 
of the wavy line s^s, s; the transverse or east and west 
excursions becoming greater the further the originating 
wave travelled south, and being both exaggerated and 
disturbed in direction, by the many curves and sinuosities 
in the mountain axis not shown in the sketch. Every 
point situated upon the limestone rock, therefore, at the east 
side of the valley was exposed to two shocks ; the primary 
in the direction nearly north to south, and the secondary 
(from the transversal vibration of the mountain chain) 
more or less oblique to that ; and these arrived, not quite 
simultaneously, but with an interval of time, as well as an 
angle of intersection, greater as the point lay further south. 
Such transversal vibration, of the almost continuous though 
sinuous ridge to the east of the valley, was of course not 
confined to the horizontal. The chocolatiere of Sig. Calvoso, 
at La Sala, gave evidence of the same in the vertical, and 
also shows that the originating wave traversed faster 
through the limestone rock, notwithstanding its loss of vis 
vivd in penetrating across from bed to bed of east and west 
stratification for so many miles, than through the deep 
clay of the Vallone. An examination of the sketch will 
also indicate the reason why the towns at the west side of 
the Vallone received so much less damage than those on 
the east side. All the feeders of the Galore fall in upon 
the west side, not a single one upon the east ; the west 
lateral range is therefore cut across by lateral valleys, 
down nearly to the level of the piano, while at the 
opposite side the range is continuous. The wave therefore 



CHTESA DELLA TRINITA— IL PONTE SILLA. 349 

was either diverted westward, or nearly extinguished at the 
western side of the valley, before it had reached far to the 
south, while at the eastern side it was carried on by the 
continuous lateral chain until changed in direction, and 
greatly diminished (by the free stratum) where the con- 
tinuity of this range is broken and terminates, near Padula. 

About a mile south of La Sala, near the military road, 
and standing at the edge of the piano upon clays of a few 
feet in depth, overlying the limestone lowest roots of the 
hills where they dip beneath the plain, stood the Chiesa 
della Trinita ; the short tower, the roof and west end of 
which have all fallen, and the walls are fissured severely. 
It is seen in Photog. No. 209 (Coll. Eoy. Soc.) looking 
westward. The tiled roof had fallen within the walls, 
leaving the tiled eaves still upon the tops of the side walls : 
its debris had been removed, but I was informed that the 
larger portion was found packed against the north flank 
wall upon the floor. The west end was thrown to the S. W. 
The east end had been kept up by cross walls external to 
it. It presented fissures, best seen at the east side of the 
wall (not shown in Photog.) which showed an emergent 
angle of 23°. The wave-path could only be approximated, 
but was a few degrees W. of north to south. 

The Ponte Silla, an ancient Eoman bridge over the 
Galore about a mile and a quarter south-west of this, 
founded probably on piles, with its heavy piers deep in the 
clays of the valley, has suffered no apparent injury by 
the shock. 



CHAPTER X. 

PADULA AND ITS NEIGHBOURHOOD — THE PALAZZO ROMANI 

AND ITS GARDENS. 



Padula, a large town, said to be of Lucanian origin, but 
with no traces of extreme antiquity, and generally well built, 
stands upon a pretty steep eminence of solid limestone, at 
the southern extremity of the first great break in the 
lateral chain to the east of the Vallone. The range rises 
high above to the N.N.E. ; and eastward of the same 
there is a narrow lateral valley in a direction about N.E., 
and exactly at the tongue, between it and the great Yallone 
stands Padula. The Yallone here narrows very rapidlj^, 
and trends off to the westward at about a mile or two 
south; and still further south at Buona Bitacola on the 
west, and Montesano on the east, it becomes quite hemmed 
in by lofty mountains. Violent contrary motions must there- 
fore have been produced by the breaking up of the great 
wave of shock in the deep alluvium, and its in-baying and 
shelving up upon the irregular masses of limestone moun- 
tains that divide the many divergent valleys, and gorges, 
and project between them. Directly south of Padula, and 
of the great Cistercian Monastery of St. Lorenzo, about a 
mile west of the town, the clays of the piano give place to 
a rolling and broken surface of clay and gravel, overlying 



TOWN OF PADULA. 351 

limestone rock at a greater or less depth, and extending for 
more than four square miles ; above which to the east rise 
the summits of Monte St. Elia, and Monte della Yajana. 
which recommence the broken chain of the E. lateral 
range* Padula therefore, has got, soft, cretaceous, and 
sandy, white limestone beds with east and west strike, and 
nearly vertical stratification to the N., similar but harder 
limestone of unknown stratification to the south, and the deep 
clays of the piano to the west of it. The rock upon which 
the town stands is of the same quality and stratification as 
the range to the north, and the coUine is joined on to the 
great range by a shoulder at rather a lower level. The 
western and southern slopes of the town are very steep, 
averaging probably 30° from the horizon towards the plain ; 
the buildings generally, either founded on the bare rock, or 
upon a thin stratum of diluvial matter, which increases in 
depth as we descend towards the plain. 

The buildings on these sides are the oldest and worst, 
and have sufiFered the most, having been exposed to the 
severest brunt of the shock, and been the least able to bear 
ity and in the most favourable position heaped above each 
other to produce mutual destruction in falling. The 
counterscarp of the town, or that on the east and N.E. 
towards the narrow valley and gorge behind it, is less 
steep close to the town, but within a quarter of a mile of 
both sides of the gorge becomes precipitous ; the west side 
being bare limestone rock nearly to the bottom, which is 
not much above the level of the piano (at the town), and 
the opposite, or east side, covered with steep banks of cal- 
careous clays ; limestone, angular gravel, and sand, getting 
Tery deep and heavy as they descend to the bottom, where 
they are being cut into and carried away by the torrent 



362 LARGE FISSURES NEAR PADULA. 

and rivers round the town to the east and south, and 
passing the Certosa de S. Lorenzo farther into the Calore. 
This torrent issues principally from copious springs in the 
rock and coming from under the clays, about a mile and a 
half up the gorge to the north ; and these are now, and 
have been ever since the earthquake, highly turbid and dis- 
Ijoloured by the reddish earth, and are said by the Syndic 
and Subjudice of Padula, who visited the place with me, to 
be largely increased in volume of water, since that event. 

The Photog. No. 210, is taken in this valley, looking 
back at the town toward the S.W. On the steep counte^ 
scarp to the right of this view I found a large fissure in the 
solid clay covering, extending some 300 yards in length at 
about 270 feet above the bottom of the gorge. The di- 
rection was due E. and W. by compass, and its S. slip vas 
from 1 to 7 inches below the level of the opposite one. 
The fissure is a flowing curve similar in horizontal plan to 
the contour of the hill side, and its line of direction is jost 
that most favourable, to a throw oflF and slip of the clay 
masses, upon the sublying rock, by the jog of the earth- 
quake, which is unquestionably the nature of its formation. 
Upon the opposite side, and about half a mile up the 
valley to the north, where the east slope has l>ecome much 
steeper, I observe with the telescoi)e that huge masses of 
clay and gravel that had stood above the torrent as nearly 
vertical banks, of from 50 to 120 feet in height over the 
water, have in several places been shaken down, and 
fallen in great masses, damming the torrent into large and 
very deep, discoloured i)ools, from some of which the dam^ 
have already given way by little debacles, while in several 
of the others, the water is escaping beneath and through the 
clay, and carrying volumes of fluid mud and sand away 




RUCK MCUILLE imp FADUIA, 




ROCK MOUllXE>v"rTN^\". 



AIGUILLE OF ROCK OVEUTIIUOWN. 353 

with it : a very few weeks with heavy rain, will carry tens of 
thousands of tons of clay and gi-avel down into the Galore. 
Higher up the gorge than the Photog. view extends, and 
upon the east flank of the gorge, this slope becomes very 
precipitous, and consists of bare cretaceous limestone, stand- 
ing up in aiguilles and isolated weathered masses, some of 
great magnitude, and here (as well as from some points on 
the rocky counterscarps of the town coUine), ponderous 
fells of rock have taken place. The massive fragments 
with newly-broken and glittering white surfaces encumber- 
ing the slope, or, after having traced their descending paths 
in lines of torn rock and furrowed detritus, block up the 
bed of the torrent below, which brawls between the 
immense fragments and beneath them. Most of them have 
been detached from the outcropped ends of the ill-discern- 
ible vertical strata, separating at joints, &c., and are mere 
eases of loss of equilibrium by the shock ; but one most 
remarkable case I observed, in which an enormous mass of 
solid rock that had stood up as a sort of blunt aiguille from 
the steep face of the slope, not quite vertical, but rather 
overhanging, (about 15° by the eye,) to the downward side, 
had been broken clean oflF at its base, and again breaking 
into three massive pieces, had slid down the rocky slope, and 
now occupied a place about 150 feet below, having crossed 
and wholly torn away the mule-path in their progress. The 
appearance of these masses, as they must have been prior 
to their fall, may be gathered from Sketch No. 211, and 
the way in which the fragments lay from Sketch No. 212. 
The aiguille, by measurements of the three principal 
fragments, must have stood about 70 feet high above its 
base when entire, and the three masses, when roughly 

VOL. f. 2 a 



354 TWO SnOCKS OBLIQUE RESPECTIVELY. 

cubed, contained fully 35,000 cubic feet, and weighed about 
2,500 tons. The surface of fracture, of which about f ths 
was formed of planes of separation (transverse joints) in the 
rock, and the remainder through the solid stone, was an 
irregular circular figure, and about 20 ft.x 18 ft., the plane 
of fracture generally being inclined about 45° to the horizon. 

The rock was very soft, arenaceous, and chalky limestone, 
perfectly white, and a hand specimen, when fresh fractured, 
could, like sugar, be rubbed away against another pieccj 
so that the cohesive energy was not great, and the inertia 
of so great and high a mass was quite suflScient, at a ven' 
moderate velocity, to bring it over. It however has a 
peculiar interest, as the first example I have seen of actual 
rock fracture by the direct operation of the shock. 

Neither the position of the centre of gravity, nor of that of 
resistance of the fractured base could be fixed with suflScient 
accuracy to enal)le any calculation to be based upon the 
fracture and fall of the mass, that would give a trustworthy 
measure of velocity or of direction. 

On examining the buildings in the town on the soutli 
and south-west slopes, where the damage done was greatest, 
I found evidence by fissures and projected wedges of 
masonry, giving a direction of wave-path varying between 
the limits of 155^ E. of north to 167° E. of north, and angte 
of emergence (all, however, proving emergence from the 
north and N. W.) varying between 20^ and 25"^. Some of 
the fractures from which the latter elements are taken 
are visible in the Photog. No. 210, though not so in its 
lithographic reproduction. 

Many circumstances indicated the transit of two shoct^ 
crossing obliquely, such as the twisting of objects on their 



PALAZZO ROMANI. 355 

bases, and the almost universal occurrence of fissures in 
aU four walls of rectangular buildings, whether cardinal or 
ordinal. 

At the very top of the town, founded upon the bare 
limestone rock, which here protrudes to the surface every- 
where, I observed an old and partly ruinous mansion, 
the Palazzo Romani, which, as well as its deserted 
gardens, afforded me some valuable data. 

The palazzo is a large, nearly square, three-story build- 
ing, very nearly cardinal. The walls are well built of 
rubble. It stands on level ground. It is fissured in all 
four external walls : all the fissures are long and thread- 
like, and are scarcely visible in the Photogs. No. 213 and 
No. 214 (Coll. Roy. Soc), the former showing the S.W. 
quoin, the latter the opposite, or N. E. one. From previous 
indications of double shock here, I dare not conclude any- 
thing as to horizontal component of wave-path, from the 
fissures in adjacent walls ; but those in the flank walls gave 
excellent evidence as to angle of emergence, which proved to 
be 25° to 25° 30' from north. The fissures in the adjacent walls 
were much more nearly vertical (8° to 10° inclination), and 
hence appeared to have been produced by the secondary 
shock, which shook the whole coUine of the town to its 
base, and therefore by an oscillation more nearly in an 
horizontal path. I could only gain access to part of the 
interior; it was empty and disused, and offered little to 
record, probably. 

In front, and to the N.W. of the palazzo, is a little 

columnar monument — II Croce Romani, of the ordinar}^ 

character ; a Roman Doric column of 9 inches diameter of 

shaft and 9 feet high, supporting a white marble ball and 

2 * 2 

mi ^^ At 



356 



IL CROCE ROMANL 



cross, and placed upon a square pedestal and plinth block, 
elevated on a few courses of rude masonry as in Photog. 
No. 215 (Coll. Roy. Soc), and Figs. 1, 2, and 3, Diagram 
No. 216. The ball and cross are secured to the top of the 
column, only by an iron dowal, and are loose ; the plane of 




Fig. 216. 

the cross has been long twisted out of square, I w^ 
informed. 

No injury has been sustained by this little structure, 
except that the pedestal has been thrown over, being lifted 
slightly at the south side l)y i of an inch vertically* 



VELOCITY THAT WOULD HAVE FRACTURED IT. 357 

as in Fig. 2, and jammed quite close to the plinth block 
at the opposite or north side. The shaft, pedestal, and plinth 
are socketed into each other, as shown, without cement. 

A vertical plane passing through the axis of the column, 
&c., in a northerly and southerly direction ranges 25° E. of 
north. The lower edge of the pedestal is lifted more at the 
western than at the eastern corner of the south side, so as 
to infer a wave-path about 10° or 12° E.of north. 

The shaft and pedestal, &c., are all of hard Apennine 
limestone, and the cavetto moulding above the base is 8i 
inches diameter only : an inference may be drawn from this 
as to the maximum possible velocity of shock, emergent 
at the angle we have found, viz., 25°, that would have left 
ihis little column unbroken at the neck formed by the 
cavetto. The horizontal velocity for fracture only is given 
by the Equation XXV. 

or 

where D, the neck of the cavetto = 0'708 feet, a, the height 
of the column adding in the ball and iron, to the cylinder 
= 6-5 feet, and L = the length of the modulus of cohesion 
for the material. This will be = 225 feet, if we take the 
weight of a cubic foot =160 lbs., and its cohesion at 500 lbs. 
per square inch (which is supported by Hodgkinson's 
ejxperimental determination for marble, 551 lbs.). Then 

225 X '708 
V= 2012 X — Tc.-^T- = "^5-961 feet per second, 

42*25 

and 
Vsece = 75-961 x 1*103 = V = 83-785 feet per second ; 

the velocity at the emergence found, that would have ju,st 
fractured the column at the cavetto. 



368 THE OVERTHROWN COLUMN 

It iSy therefore, obvious that the velocity of the shock 
was greatly below that that would have been uecesBSiy to 
fracture the column by its own inertia of motion, even if 
the cdiesion which I have assumed for the limestone of 
which it was formed be much above the truth, as is probably 
the case. The calculation, however, removes the wonder 
with which the unaided senses regard so slender a stalk 
of stone found whole and uninjured, in the midst of bow- 
ing roofe and massive walls rent or overthrown. 

In what had once been the garden of the palazzo stood a 
portion of a shaft of an old column — one of six — that had once 
formed some sort of garden edifice. It had been htckm 
off and overthrown, and afforded a precious admeasure- 
ment both for direction of wavo-path and velocity of sho<&. 

The columns had all been originally formed of an arti- 
ficial ** beton " or concrete, of broken limestone and brick, 
and lime mortar, rudely formed enough, without any base 
moulding but a fillet, and were 17 inches diameter. They 
stood upon the top course of a coutiuuous base of limestone, 
running round a large circular mised platform of earth. They 
had all been broken down and the shafts had disappeared to 
within a few inches of their bases years since, except this 
one portion of a shaft, which stood before the earthquake 
4 feet 8 inches above its base. For 6 inches in height the 
shaft was a united block, and fast to the stone base ; at 
this height an old fracture had existed, and a portion of 
shaft, 2 feet 10 inches in length, had stood upon the lower 
block, having been replaced upon it, and a little fine mortar 
interposed in the old fracture. In toppling over, at the 
north side of the column, the arris was broken out, and the 
diameter in N. and S. direction reduced to 15i inches, 
as shown in Figs. 5 and 6, Diagram No. 221. Upon the 



Ik.. 



[N GARDEN OF PALAZZO. 350 

top of this block, had stood another piece of the shaft 
1 foot 4 inches high, cemeated to it, in like manner at an old 
fractare. When examined by rae, the two upper blocks had 




Diagnm 221. 

been overthrown by the shock, and lay as in Figs. 5 and 6, 
Diagram22I,andasshowninPhotog. No. 217, having never 
been moved or meddled with, the garden being an enclosure, 
since the earthquake. The lower and longer block was, at its 
lower end, within 9 inches of the stump of the shaft The 
top block had beeu thrown over along with the one below 
it, had separated on striking the groui-d, at the top part, as 
the position of the other piece and the lower level of the 
soil than the stone base (Fig. 6) proved, and had slewed 
round and rolled a little off. The longer piece remained 



360 VELOCITY OF SHOCK 

held by its impression in the soft soil precisely in the spot 
in which it had fallen. 

The mortar joint at c, Fig. 6, had obviously possessed 
scarcely any bond whatever, and the only resistance to fall by 
the shock was, therefore, the stability of the superimposed 
two blocks upon the base or joint c. The form of the 
surface of separation, showed that the blocks had overturned 
precisely in a vertical plane, passing through the axis of 
the longer block as found prostrate, which corroborated the 
assurance of . the Syndic and others present, that they had 
not been moved by any one since their fall. The direction 
of the axis of the fallen block, B, was exactly IS"* W. of N, 
and such was the wave-path that overthrew it, the move- 
ment having been from N. to S. 

We may view the velocity that overthrew the shafts 
separately from that which projected it from its base to the 
horizontal distance given, and compounding these two 
horizontal velocities, and resolving in the direction of the 
wave-path, obtain the total velocity impressed upon it, and 
hence that of the wave itself. 

And first we obtain the horizontal velocity for over- 
turning only from the eciiiation 

,,, 15 1/ + 16 a' ,_ _ 

= ~~l2a^'~ X ^ v^ «' + ^' (1 - cos e). 

Here a = 50 indies, ft = 17 inches, 6 = lO""; and solving 
for V we have 

44335 — 

V* = 3(^^)QQ X 2-683 V 2789 (-0545) 

= 1-478 X 2-683 x 52-81 x -0545 
y = 11-42 and .-. V = 338 feet per second, 



DEDUCED FROM IT. 361 

which is the horizontal velocity necessary to overturn the 
shaft only. 

But it was also projected^ so that a point taken at the 
lower arris of the overthrown shaft had moved horizontally 
a distance of 9 inches from the corresponding point of the 
base above r (Fig. 6, Diagram No. 221), while the same 
point had descended vertically 6 inches from the arris of 
the base, as already described. Calling the horizontal 
ordinate A, and the vertical one B, we obtain the horizontal 
velocity oi projection only from the equation 



b — a tan e 

Here a = 0-75 feet, b = 0*50 feet, e = 25°-30' 
„, 32-2 0-663 



= 16-1 X 



0-500 - 0-750 X 0-4769 
0-563 



0-142 
V* = 63-756 and F = 7-98 feet per second ; 

adding the two horizontal velocities thus found, we 
obtain the total horizontal velocity impressed upon the 
shaft ; or 

F=0-38 + 7-98 = 11-36 feet per second. 

But this must be resolved to the direction of the wave-path, 
whose angle of emergence here we found to be 

e = 25°-30'. 

The velocity in this direction therefore is 

Fsec e = 11-36 x sec e, 
or finally 

V = 11-36 X 1-108 = 12-586 feet per second. 



362 OVERTURNED VASES 

feet per second, which agrees very closely with previous 
determinations from other objects and at other stations. 

The velocity thus obtained may be subject to two slight 

corrections, for which, however, the data are not obtainable. 

1st. If the mortar at the old fracture of the base had any 

adhesion at all, (I believe it had none,) the velocity due to 

fracturing it, should be added. 

2nd. The horizontal ordinate a in the last equation is 
probably a little too great as measured, inasmuch as the 
fallen piece of the shaft must, by its own elasticity and that 
of the ground, have slid forward some fraction of an inch 
after it had struck the latter, which would make the velocity 
obtained a little too great. 

These two errors, if they exist, tend to correct each 
other ; and neither could aflfect the result to the extent of 
unity in the first decimal place. The result may there- 
fore be relied upon. 

lu the same garden two vases of limestone, rudely 
hollowed out, had stood upon the opposite comers of the 
low parapet walls, that once confined the soil of beds, and 
separated them from broad walks between, now overgrowu 
with dense turf and weeds, moss, twigs, &c. 

These vases were both projected off their feet or lower 
portions, at a joint at e^ Figs. 1 and 2, Diagram No. 222, and 
thrown to the ground, the lower portions remaining still 
upon the parapets, as seen in Photog. No. 220 (Coll. Roy. 
Soc). One of the lower portions, (A, Fig. 1,) I found square 
to the faces of the parapets, and obviously unmoved; the 
other, B, had been twisted round 14°, so that two of its 
sides were in a line exactly north and south 14° W. 

The lower portions at the joint e (Figs.. 1 and 3) were quite 



IN THE QABDEN. 




364 CORRESPONDING VELOCITY DEDUCED. 

level and smooth^ and the arrises perfec); ; and the upper 
and lower parts had been merely laid together, without any 
cementing material. 

All the parts, like those of the column, &c. preceding, 
had remained untouched since their fall by the earthquake. 

The centre of gravity of the upper part of each vase, 
(that projected oflF,) I found by trial was at 10 inches 
above the joint e, and the weight by trial, was 94 rotuli = 
183 lbs. avoir, nearly. 

The vase A had been thrown so, that its centre of 
gravity had been displaced 6*50 feet in the horizontal, and 
3*60 feet in the vertical direction. We get the velocity of 
projection from the equation 

V«= ^*^ 



2 cos* e (b + atsm e) 

in which a = 6*50, b = 3-60, e = 25°-30', as before. 

Then 

42-25 X 32-2 1360'50 

" 1-629 X (lO-l X 0-4769) " 7-85 
Y* = 173 -. y = 13152 feet per second, 

which only differs from the velocity given by the fallen 
column, by 0*566 foot, or a little more than 6 inches per 
second. 

As respects horizontal direction, the vase A had been 
thrown in precisely the same path as the column preceding, 
viz., 15° W. of north towards the south; and its axis of 
symmetry was twisted as it lay, about 12° in a horizontal 
plane, from the vertical plane of projection, as seen in 
diagram, and it was obvious, from examination of the 
truf beneath, that it had not rolled after it struck the 
ground. 



EXPLANATIONS OF POSITION. 365 

The vase B, however, lay (as in Diagram) so, that its 
line of direction with its own base, was 30° E. of north, the 
horizontal range of throw being only = 4*75 feet. There was 
evidence of this vase having rolled, from the point where it 
first alighted, westward, but the precise point at which it first 
struck the ground was not decisive. It appears probable 
that it was first, along with its base, tilted up upon the edge 
// by the transverse shock through the limestone, and that 
before it had returned to its former position, the principal 
or direct shock, in the direction 15° W. of north to south, 
caught it and threw the vase oflF the base ; but part of the effort 
of projection was in that case destroyed by the fall back of 
vase and base, and hence the horizontal distance of projection 
is less than that of the other vase, and less than that due to 
the velocity of shock ; and the direction of projection became 
one in some intermediate azimuth between the two wave- 
paths. We might assume that the vase, B, was projected by 
one shock, and that, A, by the other ; in which case we could 
infer that the angle of horizontal intersection of the wave- 
paths had been = 45°, but that would render no account of 
the twisting of the base of B. We must, therefore conclude, 
that the vase B was acted on by both shocks, and as it had 
rolled more or less, the angle of intersection would be less. 
The supposition made, also gives . a. solution for the fact 
otherwise hard to account for, that the part of this vase 
that rested on its base was towards the south as it lav, while 
the ijqfjjesponding part of A faced the north. The latter 
was a clean throw j in the former the vase was tilted a little 
towards the N .E. in the return to its place, of its partly- 
upturned base, immediately previous to its throw, and the 
rotation thus commenced, turned it over in a vertical plane 
during its free descent from its base to the ground. 



3G6 ARCH KEYSTONES WORKED UP. 

It will be seen, on looking at Fig. 3 (Diagram No. 222), 
that the vase might have been thus tilted apoo its own 
base at the joint e, to the extent of nearly 22° 30', before 
it would have lost the power of recovering its position, and 
that when tilted through part of this angle, the effect of the 
throw of the second shock delivered to it through the base, 
would tend to increase the rotation commenced, as well as 
to diminish the extent of horizontal range, or veloci^ 
impressed. 

The general relation of till these objects as to azimuth, 
is shown in Fig. 223. 







Fit;, -i'^ 

I found hero also, as at Polla, an example of that sin- 
gular circumstance, the keystone or block, of a cut stone 
semicircular arch over a doorway, Avliich had worked up in 
place of coming down (by the niovcraents of the earth- 
quake) between the remaining arch stones. This case, of 
which the (original) Sketch No. 224 is a true representa- 
tion, (though very imperfectly given by the woodcut.) is 
obviously duo to the rocking to and fro of the whole widl 
in the plane of the arch, the motion being several times re- 
peated, and hence the alternate partial freeing and gripping 
of the keystone, at a and c, b and </, between the rocking 
vonssoirs, which, moving on the lowest point of the jambs, 
or at the springing level, are thus at each oscillation, i-ela- 
lively higher and lower than each other, at d and at n. The 



PHENOMENA EXPLAINED. 



keysfcoDe at each alteniation, if already tolerably free above, 
by the fractures of the wall, produced at the first moment 




of shock is thus moved up more or less, and finally remains 
at the height gained. 

In this instance, the keyblock had been thus lifted up, li 
inch above its former place. It is an excellent example, of 
one of the many cases, in which a misinterpretation of the 
phenomena, or misconception of the forces, &c., produces 
felse notions as to the actual movement, of the shock pro- 
ductive of them. My attention was drawn to these arches, 
here and at PoUa, by intelligent men (Syndici and Judici, 
&c.) as affording proof positive, of a sudden dropdown, or 
jump up vertically, of the earth and the buildings upon it. 



370 ITS RUIN DESCRIBED. 

Diagrams Nos. 238 and 240. Its architecture will be 
gathered from the several Photogs., &c. It is shattered 
and shaken to its foundations in every portion, by the 
violent effort of the earthquake, and presents character- 
istics of much more formidable dislocation, than the town 
of Padula did. 

All its walls, its vaulted church, and refectorj^ and very 
many other grand roofs, the noble groining of its cloisterBy 
and the painted and richly stuccoed ceilings of its library, 
and of many a royal chamber, are split, fissured, and fiedling. 
The light and the rain now find their way through acres of 
shattered tiling. Innumerable chimneys, obelisks, parflpets, 
vases, bassi-relievi, statues, are thrown down, disfigured or 
destroyed. Even the internal fi^aming of the heavy- 
timbered roofs^ has been in several places crashed, by the 
fall of heavy masses from above. Nearly all the superb 
columnal arcades around its cloistered courts, are bulged at 
tlie groining levels, and lean out towards the court. The 
groining is split along the soffits in almost every gallery 
except one, where alone iron tye-bars across the ardh 
chord (originally placed in all), remained, after the Frendi 
division that was quartered here ; a proof of the value oC 
such bars in seismic construction, as well as in the eyes of 
the brigands that pillaged them. 

Opposite the front entrance gate of the monastery, at 
D, (Diagram No. 240,) but at a considerable distance to the 
south beyond what the diagram admitted, stands a mom- 
ment to St. Bruno (Photog. No. 225). The general pliM 
of the structure runs east and west almost exactly, Sev^ 
of the little obelisks and finials upon it, have been twisted 
from left to right (looking south at it), or in the same direo- 



'^l 




^Y^ksi-n ^ 



SPECIALITIES OBSERVED. 371 

tion as the hands of a watch move. Some of its smaller 
are thrown down. 

In the entrance square, within the walls, as seen in 
Photog. No. 226 (Coll. Roy. Soc), looking south from the 
steps S (Diagram No. 240, Fig. 1), the whole of the square 
pyramidal chimney caps upon the east side building, from 
B to B, are thrown down, and on to the roof tiling ; and 
several of the balustrades and finials over the mural foun- 
tain, in the centre of the length of this side, are twisted 
also. 

The great axial line of the whole mass of buildings is 
north 5° W. 

The chimney caps B B, 13 in number, are thrown to 
various horizontal distances, varying between 3 and 5 feet, 
on to the tiling, as in Fig. 2 (Diagram No. 240), but all 
with a very nearly uniform direction of 136° E. of north. 
None of the chimney shafts, which stand about 5 feet above 
the roof, have been overthrown, though some have been 
shattered at top by the chucking oflF of the caps, which, 
like the shafts, are of brick set in mortar. 

Entering the front court or square, the campanile is over 
the south-east comer, as seen in Photogs. No. 227 and 227 
bis (Coll. Roy. Soc.), and from the summit, two large balls, of 
stone, A and B, have fallen, one of which, with its pedestal A, 
remains buried amidst the broken parts of the roof upon 
which it descended, while the other, B, falling without its 
pedestal (which still is in situ), upon a more solid part of 
the roofing, rolled down over the eave, and described a 
trajectory fromBtoB\ (Figs. 1 and 2, Diagram No. 238), 
down into the marble-paved court, breaking the nosing of 
the step at B^ rolling thence across to B*, and striking the 

2b2 



372 



THE CHURCH— TUE REFECTORY. 



base of the fountain, "made a cannon'* over to B*, where 
it remains. 

In the north-west corner of this square, beneath the 
arcades of the west side, a statue of the Madonna, standing 
in a niche, has been twisted on its base, and shifted in a 
final direction, 115° E. of north, as seen in Photog. No. 228 
(Coll. Roy. Soc.), and Fig. 3, Diagram No. 240. 

Very near the Campanile, but far below its summit level, 
upon the east gable of the front range of buildings, at F 
(Fig. 1, Diagram No. 238, and Fig. 4, Diagram No. 240), 
are two remarkable chimney stalks, one of which has been 
twisted upon its base, at a horizontal fracture close to the 
level of the gable, the other standing uninjured. 

To the eastward of the front square, the roofs of the church, 
and of the grand refectory, groined and arched buildings of 
great magnitude, have been heavily fissured. In the refec- 
tory both end gables, (Fig. 239,) run up originally against 
the ends of the brick vault, have parted off from it, and pre- 




3J?!V/^{JW/mW^#':*i7/SJ Vf^V 



Fig. 239. 

sent east and west fissures, open 3 inches at top on the north, 
and 13 inch at the south end, while longitudinal fissures of 
half an inch to one inch wide run north and south along the 
sofiit. The roof of the church is still more dislocated ; both 
roofs are brick vaults. At the upper end of the refectory 
the great fresco by P]lia, of the Marriage of Cana, is fissured 



THE GREAT SQUARES— THE GARDEN, 373 

and nearly destroyed. Photog. No* 229 (Coll. Roy. Soc.) 
shows this, and the great vault fissure at the end. 

In the Priors' Square, one of the most richly decorated 
portions of the monastery, the whole of the buildings are 
in a felling state, the vaulting of the surrounding arcade 
being split on each side of the square, the north and south 
sides, most formidably, and next to these the east side, the 
front pilasters and the story which they carry above them, 
all leaning out, and heavily fissured, as in Photogs. No. 23 1 
and No. 232 (Coll. Roy. Soc.) 

Entering the great square to the north-east of the last, 
which in magnitude rather seems the " place d'armes" of 
some immense " caserne," than the court of a monastery, 
the groined arcades are similarly fi^ctured; the pilasters 
and story above, bulging out into the court, are seen fi-om 
within, and from without, in the line of one of the galleries 
in Photogs. No. 233 (Coll. Roy. Soc), and No. 234. 

To the westward of the great square, in the private garden 
of the "Priure," amid much other destruction, a lime- 
stone vase has been thrown, from the summit of the south 
pier of the gate at the west side of the garden, as seen in 
Photog. No. 230 (Coll. Roy. Soc ), and in Figs. 1, 5, and 6, 
(Diagram No. 240), the direction of throw 122° E.of north. 

The blocks of stone of the pier itself have been thrown 
or shoved upon each other, eastward about half an inch, 
and the whole of both piers more or less dislocated. 

I have thus briefly recapitulated the objects to be spe- 
cially referred to, for the information they convey. The vast 
mass of buildings, however, presented almost an unvarying 
spectacle of destruction — few of the walls or roofs actually 
prostrate, but everywhere fissured, dislocated, and tottering ; 



374 THE GRAND ESCALIER. 

all their beauty, and magnificence of architectural form and 
coloured decoration still addressing the eye, but along with 
gaping rents, that sadly told that their glory was departed ; 
if repair were possible the vastness of the cost precluded 
it ; and thus in a few years hence, the work of one terrible 
hour, will have made the owl and the bat, the tenants of 
this Cistercian palace. 

Almost the only part of the edifice that has escaped 
serious injury, is the grand elliptic staircase leading to the 
park, at the extreme northern end. This noble work, said 
to have been constructed from a design bjr Buonarotti, is 
built of fine sawed ashlar, in the hard white Apennine lime- 
stone, everywhere polished withinside. Its preservation 
seems to have arisen from its form, the support to the 
north given by the broad flights of steps within and with- 
out, and the careful nature of its workmanship. 



CHAPTER XII. 

FIRST DEDUCTIONS PROM FACTS OF THE CERTOSA — 

DOUBLE SHOCKS. 



I NOW pass to the deductions to be obtained from the 
observed facts here. 

There is evidence everywhere, of a double if not a triple 
shock, confirmatory of the statements made at the town of 
Padula, of oscillation in various directions. The main shock 
was in the primary wave-path, right along the Vallone 15^ W. 
of north towards the south, and arrived, through the deep 
clays and loose material of the plain. This was preceded at 
a very brief interval by a secondary shock, transverse in 
path to this by a certain angle, and derived from the 
lateral vibration of the mass of limestone mountain on the 
range to the north-east. Lastly, the primary shock appears 
to have been reflected, from the abrupt neighbouring moun- 
tain further south, and to have returned again, as an earth- 
qtmke echo, through the clays, with very diminished force, 
arriving last upon the scene. 

Referring to the Photog. No. 225, of the monument of 
St. Bruno, it will be seen that many of the obelisks and 
finials are twisted, and some are overthrown. We have 
universal evidence of the shock, in the path 15° W. of north 
to south. Here the finials which are overthroum are thrown 



376 MECHANICS OF THE TILTING 

directly westward. All those that are twisted are turned 
from left to right. 

Now there are two distinct trains of earthquake causa- 
tion, by either of which bodies may be twisted on their 
bases. 1st. By the action of a single shock, when the 
centre of adherence of the base of the object, lies to one side 
or other of the vertical plane passing through the centre of 
gravity, and the line of the wave-path. 2nd. By the 
conjoint action of two closely successive shocks. By the first 
shock, the body is tilted up from its base, but not over- 
thrown, so that for a time greater or less, it rests wholly 
upon one edge of its base ; while thus poised, if another 
shock bear upon it, in any direction transverse to the first, 
it acts as usual at the centre of gravity of the body, to 
displace it by inertia, in the contrary direction to the wave 
transit ; but the body is held more or less, by friction at the 
edge momentarily in contact with its support, and there only ; 
but this edge must always lie to one side of the vertical 
plane passing through the centre of gravity, in the direction 
of the wave-path : hence the tilted body, while relapsbig 
upon its base also rotates^ round some point situated in the 
edge of its base upon which it had been tilted, and thus 
it comes to rest iu a new position, having twisted more or 
less round a vertical axis. 

If the observer look due south at a square pyramid, for 
example, whose sides stood cardinal, and it be tilted by the 
first semiphase of a shock from east to west, the pyramid will 
tilt or rise upon the eastern edge of its base ; and if, 
before it has had time to fall back, it be acted on by another 
shock from north to south, the pyramid will rotate, upon 
the bisection or on some other point, of the edge on which 



AND TWISTING OF OBJECTS. 377 

it momentarily rested, and will hence come to repose, after 
having twisted from left to right, or with the hands of a 
watch. 

If the tilting up, had been produced by the second semi- 
phase, of the same shock from east to west, then the pyramid 
would have risen upon the western edge of its base, and 
the same direction (north to south) of second shock, would 
have produced rotation upon that edge, but in a contrary 
direction to the preceding, or from right to left, or against 
the hands of a watch. 

Again, if, on the first supposition, the/r.§/ seniiphase of 
the east to west shock, had tilted the pyramid upon its 
eastern edge of base, but the second shock had been from 
south to north, in place of the reverse as before, then the 
rotation would have been from right to left ; and if tilted 
by the second semiphase on the uoestem edge, the second 
shock, south to north, would produce rotation left to right. 

It would therefore appear at first impossible, to deter- 
mine the direction of motion in transit, of either shock, from 
such an observation : we can, however, generally discover 
upon which edge of the base any heavy body of stone or 
masonry has tilted, by the abrasion or splintering of the arris, 
and the rotation must have taken place round some point in 
that edge. If, therefore, we know the direction of either one 
of the two shocks, we can always discover that of the other, 
by the rotation observed ; and if the time of oscillation of 
the body be ascertainable, we are enabled to calculate a 
major limit, for the interval of time that must have elapsed, 
between the arrival at the twisted body, of the first and of 
the second shock, when both the wave-paths are known. 

With a single instance of such twisting, it may be im- 



378 WHEN DOUBLE SHOCK NECESSARY. 

possible to decide, whether the twist has been due to one 
shock, (1st case) or to two shoclis in succession, (2nd case); 
bat when several bodies alike or dissimilar, at the same 
locality, are aU found tunsted in one direction, it is certain to 
have been the work of two distinct s/u>ch, for it is beyond the 
reach of probability, that several bodies, should all happen to 
have their respective centres of adherence, at the same tidt 
of their respective centres of gravity, and unless they have, 
some will rotate in one, some in the other direction by any 
single shock; rotation thus produced, being always by the 
centre of gravity, moving contrary to the first or second semi- 
phase of the wave, and carried round the centre of adherence, 
by the line joining them as a radius vector ; the inertia of 
motion at the centre of gravity, and the resistance of the point 
of rotation in the edge of the base, or of the centre of adhe- 
rence, forming in every case, the extremities of the dynamic 
couple. 

All the effects of the double shock will be understood by 
examination of the Figures Nos. 235 and 236, in which 




Fig. 235 shows the action of any double shock ; Fig. 236 fiie 
variations of result (iroduced, tiret, hy rotation in the fii'sl 



VARIED CONDITIONS EXPLAINED. 



379 



semiphase A, and second semiphase B, by the same double 
shock ; secondly, the like by rotation, iu the first semiphase 
(C), the first shock being as before, but the second, con- 
trary in direction to that of the previous cases (A and B), 
and the like for the second semiphase (D), the two shocks 
being the same (C and D). 



l^At^ 




B f^Aaek 



xuyr. 



H 




Fig. 236. 

Applying this to the facts at the monument of St. Bruno. 
AU the finials, &c., are twisted from left to right; we 
know that the main shock was from 15° W. of north to the 
south, it therefore follows, that the shock which first moved 
them, arrived in a path somewhere between that, and from 
east to west : by this they were tilted ; by the immediately 
following shock, 15° W. of north to south they were twisted. 
Neither shock was sufficient, in velocity or range, com- 
pletely to overthrow any of them, except those which were 
top-heavy, by having had balls at their summits, which 
have, except in one instance, been all dislodged. 

A great many pyramids and finials on the top of the 
fountain in the entrance square B, Fig. 1, Diagram No. 240, 
and Photog. (Coll. Roy. Soc), presented precisely similar 
phenomena, as did those on the parapet of the great facade 
Photog. (Coll. Roy. Soc), and in divers other places. 



880 



APPLICATION TO THE CHIMNEY 



The complex forms of these objects^ which rendered Ae 
aseertamment of the positions of tiieir centres of osdllation 
on the edges of their bases^ difficult and nncertain, nnleasby 
experiment^ prevents any calculation of a precise cliaractei; 
from tiieir movements, as to the velocity of either ahocki 
nor do we require it. 

They give us other valuable information, however. In 
the case of the parallelopipedal chimney, (F. Fig. 1, DiagrBm 
Nos. 238-240, and Fig. 4; same diagram), twisted upon its 
base, it had rotated upon a point in the western edge of its 
base at i. Fig. 237. We know already that the directicm 
(generally) of the first shock, was from some points east or 
N.E. towards the west or S.W., the second being from 
IS"* W. of north to south. The chimney stalk had therefore 
made, one a^mi-oscillation, and one complete oscillation; that 
is, it was being acted on by the aecond semiphase of flie 
wave of the first shock, at the moment when the second 
shock arrived at it, as in Fig. 237. 




The centre of oscillation of the chimney above b thus 
tilted was, as nearly as could be ascertained, 4*33 feet distant 
from the edges of the base upon which it tilted 6 and 6j. 
The first shock, east to west, fractured the chimney from 
its base, and produced in the detached chimney, one semi- 
oscillation eastward (A, Fig. 237). The chimney then 



AT THE CERTOSA. 381 

relapsed upon its base (B), Fig. 237, and rising again upon 
the edge 6^, leaned over westward (C), Fig. 237, having thus 
made one complete oscillation in that direction, with the 
moment of repose (B), when it had fallen back plumb upon 
its base. Between that moment of repose, and the comple- 
tion of the oscillation, or almost instantly after it had com- 
menced to fall back (C) from west to east, to reassume its 
original position of repose, the second shock from the north 
to south reached it, and twisted it round horizontally, in the 
manner that has been already explained. 



CHAPTER XIII. 

DEDUCTIONS FROM FACTS PRESENTED AT THE CERTOSi, 
CONTINUED — INTERVAL OF TIME BETWEEN THE FIRST 
AND SECOND SHOCKS CALCULATED. 



We can calculate, therefore, from these data, to a good 
approximation, the interval of time that elapsed, between 
the arrival of the first and second shock, and thence the 
diflFerence in transit velocity, of th^ two waves of shock ; 
the first through the limestone, the second through the deep 
clays and gravels, &c. 

The chimney may be regarded as a parallelepiped vibratr 
ing as a compound pendulum, upon 6, and h^ (Fig. 237) 
as points of suspension, whose centre of oscillation is in the 
plane of shock passing through the centre of gravity, aud 
distant from b or h^ by two-thirds of the diagonal of the 
parallelopiped, in the same plane. 

This distance = 4*33 feet is the length of the corresponding 
simple pendulum, with some small allowances for the hollow- 
ness and irregularity of form. The greatest possible arc of 
vibration, is limited by that which would bring the centre of 
gravity, c, vertically over h and 62, Fig. 237, beyond which 
the mass must have fallen. This I found to be 21°, at 
either side of the vertical through the centre of gravity, 
when the chimney was in its original undisturbed state. 

The arc actually described, must have been less than this, 



Oscillation of the chimney stalk. 383 

and from other observations yet to be referred to I conclude, 
that this arc was not more than 15° at either side the ver- 
tical, or with a horizontal chord at the centre of gravity 
of about 12 inches. We shall not make a sensible error, 
however, by assuming the arc described, as the largest 
possible. 

Taking the time of oscillation from the equation 

FT /- a 9 a* \ 

where a — ver sine of half the arc of vibration ; we have 

or = 3-14 X -3668 x 1-0019 approximately, 

and T = 1*536 seconds ; 

correction for latitude being needless. 

From the moment of arrival of the first shock, up to 
the arrival of the second transverse to it, the chimney 
had made, one half and one complete, vibration, and 
possibly had just commenced another. At the moment 
that the chimney relapsed upon its base it lost via vivd^ and 
therefore time, before it rose again, to complete the arc west- 
ward This minute loss of time we can only estimate, 
because although we know the velocity at the moment the 
mass of the chimney struck its base, on resuming the per- 
pendicular (B, Fig. 237), we do not know its hardness, 
elasticity, &c., upon which that loss also depends. 

Neither can we calculate precisely, how much of the com- 
mencing arc of the third oscillation had been performed (if 
any), before the second shock reached the chimney, because 
we do not know the precise point round which it rotated, &c. 



384 DIFFERENCE IN TIME BETWEEN THE SHOCKS. 

But where the arc of horizontal rotation is great, as it 
is in this instance, where the chimney was twisted round 
30° to the westward, the latter must have been extremely 
small or nil. 

Calling these two small corrections d and /, the whole 
interval in time I, between the shocks is 

l^T + ^ + d+f. 
We therefore obtain 

or without the two latter, 

I = 1-7304 seconds, 
and estimating cZ, assuming / as small =0, we may consider 

I = 1*75 seconds. 

This is the difference in time, between the arrival of the two 
shocks ; both of which started at the same moment and from 
the same origin. The evidence for the position of the latter 
has yet to be adduced ; anticipating the fdct^ however, 
the Certosa, is distant from it, 16^ geographical miles, or 
33,415 English yards in the right line, which was the path of 
the second shock, arriving directly 15° W. of north to south, 
through the deep clays and gravels, &c., of the Vallone; 
while that of the first shock, was through the east lateral 
range of solid limestone mountains, but whose length (as 
respects the wave-path) we may consider as one-fifth of a 
mile greater. 

From facts (also yet to be adduced), I found that the 
general velocity of tramlation of the wave of shock, through 
the limestone country, was at the rate of 240 yards per 






WAVE TRANSn^S THROUGH LIMESTONE AND CLAYS. 385 

second. This, therefore, may be taken as the velocity of 

translation of the first shock here (through the limestone) ; 

the total time of its transit from the origin (surfe,ce velocity) 

is therefore 

33415 ,,, ,,^ 
-— -- = 139-230 seconds; 
240 ' 

and through the clays and gravels the whole time is 
139-230 + 1-750 = 140-980 seconds. 

The velocity per second of surface translation in the clays 
and gravels was therefore 

33415 + 402 ^o^«, ^ 

——r, = 239-84 yards per second. 

141 

The shock through the limestone reached the Certosa 
from the Colline of Padula, the nearest point of rock in 
the path, through an intervening stratum of clays and 
gravels, by which there must have been some loss of 
tris vivd. If we throw oflF the decimals for this correction, 
which we can only estimate, we have finally, for the 
surface velocity of translation, 240 yards per second in the 
limestone, and 239 yards per second in the clays and gravels, 
D^easures approaching so nearly to equality, as to warrant 
one or both of the following conclusions. 

Either, the main primary or direct wave arrived, like the 
other through the limestone formations, deep beneath the 
clays and gravels of the piano, and shook the latter resting 
upon them, at their own rate of translation nearly; or 
(here at least), the bedding-joints and other breaches of 
homogeneity in the limestone rock produce a retardation 
of the wave transit therein, such as reduces the velocity to 
nearly that in jthe dense clays and gravels. In this ex- 

VOL. I. 2 c 



386 PROBABLE CAUSE OF NEAR EQUALITY. 

tremely dislocated and overturned country I deem the 
latter as most probably the fact. 

The measures of velocity for this locality are relatively, 
however, as nearly reliable as the data will admit. As 
absolute measures of transit velocity, they must be taken as 
mere approximations, as all our data for this are based 
upon the observations made as to time at the moment of 
shock, and unfortunately are not only few in number, but 
by no means to be relied upon as to exactness, in this 
locality. 



CHAPTER XIV. 

DIFFERENCE IN AZIMUTHS OF PRIMARY AND OF 

SECONDARY SHOCKS AT CERTOSA — 

ANGLE OF INTERSECTION. 



I NOW proceed to consider the angle of intersection in an 
horizontal plane, made by these two shocks at the Certosa. 
Referring again to the two great stone balls (one along 
with its base) projected from the top of the Campanile upon 
the roofs of the front square, (Fig. 1 Diagram No. 238 and 
Diagram No. 240, and Photog. No. 227 (Coll. Roy. Soc.) 
in which the ball B is seen lying, where it fell), we are 
enabled from these to infer the wave-path of the first shock 
with some certainty. 

Both balls were projected from the Campanile in a 
direction 64"^ W. of north, and precisely alike. 

The first shock, arriving from somewhere between 
north and east, caused the Campanile to oscillate from west 
to east and east to west ; i. e. in the line of its narrowest 
dimension of base. 

The balls were thrown off in the second semiphase of 
the wave ; therefore, and as the time of oscillation of the 
tower (from its altitude) was large, and greater than that 
of the whole phase of the wave they were projected with a 
velocity less than that due to the shock ; the top of the tower 

2 c 2 



388 VELOCITY OF FIRST SHOCK 

moving, by its elasticity and inertia, towards the east, 
at the same time that the forward movement of the whole 
mass towards the west, by the wave of shock, projected 
the balls with a velocity equal the diflFerence. 

We shall take the velocity from the ball B, which fell 
unencumbered by its base, and whose mark where the 
sphere struck and fractured the tiling of the roof, at B, 
(Fig. 1, Diagram No. 238, and Fig. 2, Diagram No. 240,) 
left no doubt as to its precise range. 

This ball was projected a horizontal range of 12 feet, 
along the plane of projection, and descended vertically 
42 feet from the summit of the Campanile to the roof 
tiling. 

We may assume the angle of emergence for this shock 
e - 20°, the same as that of the primary shock (15° W. of 
north to south) here ; because although coming from the lime- 
stone in which (at Padula) we found the emergence greater 
= 25° 30', yet we are here some hundreds of feet lower, 
and the shock, in passing from the limestone into the clays 
and gravel, intervening before reaching the Certosa, must 
have sufiFcred some refraction into a rarer medium, both 
tending to reduce the value of e. 

Both these balls were attached to their pedestals or bases 
by a small wrought-iron dowal inserted into both, suflBcient 
in strength to communicate its velocity from the base to 
the ball, but permitting easy separation of the two (/. e. 
ball and base) when not rusted into the sockets. It was so 
rusted, in the ball A which fell with its base, but in B, the 
dowal, which was about half an inch diameter, was found 
broken off, either previous to, or during the fall of the ball. 

It must be borne in mind, in considering what follows, 



DEDUCED FROM BALL OF CAMPANILE. 389 

that these balls, and more particularly that B, were 
projected by the transverse shock, the impressed movement 
being therefore in the same direction as that of the wave, 
but had their plane of projection altered by the immediately 
following main shock, which, acting on them by inertia, 
impressed a movement in the contrarij direction to that of 
the wave. Unless this were understood the path obtained 
by the following method would appear erroneous. 

We obtain the velocity of projection from the equation 



2 cos^ 6 (6 + a tan e), 
in which e = 20°, 6 = 42 feet, a = 12 feet, 
and V = 1154 feet per second. 

This was the velocity in the plane of projection 64° W. of 
north, but this direction was not that of either shock but a 
resultant of both, the ball having necessarily received a 
certain amount of impulse from the first shock, and before it 
had completely parted hold from its support, been exposed 
to the impulse of the second. Now the direction of the 
second (i. e. the main) shock was 15° W. of north to south, 
and we have already ascertained at several points that its 
velocity was 12*97 feet per second. We have, therefore, 
two velocities, and the direction of the resultant, and of 
one component given, to find the direction of the other 
component. 

Resolving, we find that the transverse shock made an 
angle with the primary or main one of 56° 40', and that 
the wave-path or direction of the former was 41° 30' E. of 
north to south, which is precisely the direction of a line drawn 
firom the extremity of the mountain range northward and 



390 FINAL DEDUCTION, AS TO BOTH SHOCKS. 

eastward of Padula and to the Certosa, as may be seen by 
examining Zannoni's great map (Sheet 19). The range, 
after running nearly north and south, terminates at Padula, 
after having made an abrupt bend to the westward in the 
above azimuth (by compass) from the Certosa. Hence it is 
to be inferred that the transverse shock (the first in point of 
time) was delivered from the free extremity of the range of 
limestone mountain, along the axis of which it had followed, 
while the great primary or direct shock (the second in point 
of time) came normally through the clays, gravels, and 
other formations, beneath and in, the Vallone di Diane, 
both intersecting at the Certosa. 



CHAPTER XV. 

FURTHER DISCUSSION OF OBSERVATIONS MADE AT THE 

CERTOSA AND AT PADULA. 



At Padula, while the main wave-path was unmistakably 
IT*' W. of north to south, I found fissures giving extremes 
of directions from 155° E. of north to 166*' E. of north, 
and evidences of a very subordinate vibration nearly from 
west to east. The latter, it is highly probable, was due to 
the partial dispersion of the main wave of shock, as it 
reached the southern head of the great valley, and passed 
from its deep formations out into the limestone mountains 
that shut it in to the south. 

I had also evidences of such subordinate movements, and 
more distinctly marked, at the Certosa, 

The great fissures here, by the very construction of the 
buildings, ran principally east and west, and north and south; 
the former being by much the wider (transverse to the main 
shock), but the abutting of the several masses of building 
upon each other, very generally preventing that freedom of 
motion, that is essential to enable deductions as to wave- 
path to be made thus with precision. From some of the 
main buildings, that rose free and unencumbered above the 
level of the surrounding ones, however, I obtained measures 
of direction, the extremes being 116°E. of north to 165°E. 



392 



GABLES OF THE REFECTORY. 



of north ; and although very wide in limit, and often per- 
plexed, from the complicated movements to which this place 
had been subjected, all were confirmatory of the general 
wave-path obtained at the Francescani already given. 

The most instructive fissures I found, were those by which 
the two great gable walls of the refectory had parted oflf 
fi'om the ends of the semicircular vault which formed the 
roof. An interior Photog. of this noble hall is given 
(No. 229, Coll. Eoy. Soc). The soffit of the vault was 
fissured in a north and south direction from end to end 
nearly, and half to one inch wide. 

The gables were great semicircular walls of rubble stone- 
work, run up firom the chord-line or level of the springing, 
after the vault had been turned, and merely closed in against 
the ends of the arch, as in Fig. 239, not being bonded into 
it. Each of these gable walls had gone out at top from the 
end of the vault, producing a gradually widening and tre- 
mendous fissure, which, at the north end, was open 5 inches 
at top, and at the opposite, or south end, 3 to 3^ inches. 




^fe^^^^^B^ 



^ 









Fig. 239. 

The gables, thick, heat y, inelastic, and yielding, from the 
bad rubble of which they are built, had bent over from 
above the chord-lines, showing innumerable minor thread- 
like fissures of dislocation in the work, more or less hori- 
zontal ; neither had approached within some inches of the 



AMPLITUDE OF THE WAVE DEDUCED. 393 

limit of stability. The north gable wall had given out in 
the first semiphase of the shock, the south in the second semi- 
phase ; and both appeared, from the fragments fallen into the 
fissures, none of which were crushed, or gripped and pressed 
into compacted powder, (as is not unusually the case,) to 
have gone out very little, if at all further, by the impressed 
movement, than where they stood as I examined them. 

The width of this north fissure, therefore, afibrds an 
approximate measure, of the actual amplitude of the main 
wave of shock here ; for the opening, or the actual movement 
of the gable, at the level of its centre of oscillation, upon 
the chord as axis, must have been about equal to the am- 
plitude of the wave, taken in a horizontal line. It would 
be useless, upon inexact data, to pursue this minutely ; we 
may conclude, however, that the horizontal amplitude of the 
main wave of shock here, did not much exceed 4 inches. 

There were also immense fissures, in the 9-inch brick 
groining of the roof of the church, both longitudinally and 
transversely through the axis. The beautiful domed cupola, 
also presented complicated fissures, but was in so tottering 
a condition as to prevent close examination ; all these indi- 
cated a principal wave-path some degrees W. of north to 
south. 

The urn or vase, thrown from the summit of one of the 
gate-piers, in the garden of the Priure, Photog. No. 230 
(Coll. Roy. Soc.), and Figs. 1, 5, and 6, Diagram No. 240, 
presented a good example, of the iffgh velocity with which 
bodies thus placed on the summits of slender vertical 
erections, may be projected by the elastic vibration or 
rocking communicated by the shock to the erection itself. 
This vase was thrown nearly in the same path as the balls 



394 VASE OF PRIOR'S GARDEN. 

from the Campanile, but in the opposite direction. Its path 
was 58° W. of north to south. 

It was, no doubt, thrown off by the recoil of the pier 
upon which it stood, when making its second osciUation, pro- 
duced by the first shock (41° 30' E. of north to south), when 
the main shock reached it, which increasing the movement 
already impressed, and at the same time changing the 
plane of projection, threw it to an horizontal range of 
18 feet, from an elevation on the pier of the same (18 
feet). 

Assuming e= 20° as before, we have from the equation 

V^ — - ^ 



2 cos^ e {b + a\SiVL eY 

the velocity of projection of this vase, 

V = 21-23 feet per second, 

which is about Si feet per second in excess of that of the 
wave of shock, the difference being due to the angular 
velocity of elasticity acquired by the pier itself, added to 
that of the wave. In fact, in such examples, the body 
thrown is projected like a stone from a sling. 

There was every reason for my believing that the vase 
remained where I found it, half embedded in a flower- 
border, in the locked-up garden of the prior, and untouched 
since the earthquake ; and the splintered and disjointed state 
of the limestone blocks of the pier, itself indicated the extent 
to which it had vibrated. The corresponding vase was not 
thrown though loosened, nor was the pier as much shattered, 
though I could not discover any very certain cause for the 
difference in effect upon both. Each vase had been steadied 
when in place by a slender iron dowal. 



THROWN CHIMNEY CAPS. 395 

I have stated that there was evidence of a third shock, 
diflFerent in direction from either of those already considered. 
This was visible in many small objects, which gave indi- 
cations of disturbance, by the main shock or by the trans- 
verse one, and also of immediately subsequent disturbance, 
by another, or by several other minute vibrations or little 
shocks, in directions from south to north, varying 10° to 
15° to the east or west of that. This last shock, or jarring 
succession of shocks, appears to have been a true earthquake 
echo^ or reflection of the main shocks back, from the 
limestone mountains to the S., S. W., and S. E. of the 
Certosa. 

In the line of buildings to the east side of the great front 
entrance square, between B and B (Figs. 1 and 2, Diagram 
No. 240) a great number of pyramidal brick chimney 
caps were thrown oflf from the tops of the stalks, in a 
general direction to the S. E. The mean direction of 
their throw I found to be 136° E. of north, which is one 
not so widely diflFerent from that of the resultant path 
of projection due to the two main shocks, but that all of 
these might have been projected oflf at the same moment 
and by these shocks ; the diflferences in direction being 
due to the irregular figure of the pyramids, and to their 
ordinal position with reference to the resultant path, as well 
as to their having in some cases probably slided after their 
fall upon the sloping tiling of the roofe. The position of 
several of these caps, however, and the wide diversity from 
the resultant path of others, caused me to conclude that 
several of them had been loosened by the main shocks, and 
afterwards overthrown by this third movement in reverse. 

To the same repetition of movements I attributed the sin- 



aw MOTEMEin^ OP THE HASONNA. 

golar di^lacanent of tbe limestone statne of the Madonofti^ 
(Photog. No. 228 (Coll. Roy. See.) and Fig. 3, Diagram I 
240), vhich I foand had moved upon its pedestal, without^ 
iignij or overthrow, about 1| inch in a direction 115" 
nwQi towards tiie S. £. Its base was an irregular oct^ 
The figure had been twisted a little in a direction from r 
towards east, orwitii the hands of a watch ^ and its displa* 
ment ^^>eared to have arisen, from its having rocked 1 
conical pendolom, round the successive sides and angles a 
its octagon pedestal, which the base of the figure ovei 
hong: by the co^jomt influence, of the intersecting shock! 
and the centre of gravity of the figure being not over t 
centre of the base, bat nearer to the S. E. side (at t 
die infiuit rests in the Madonna's arms), the circle of i 
tkm tended to this side, and as the figure passed round c 
ai^fi at tJiat side of the pedestal, it gained a little ^ 
towards the direction in which I found it had shifted. The ' 
friction between the pedestal and base, there being no cement 
and both smooth, being small, it would be possible for a 
figure of this sort, however, to shift its position by merely 
rocking to and fro in one plane at first, the lower part 
shifting forward at each return oscillation, by the existence 
of a centre of "spontaneous rotation" between the centre 
of gravity and base ; and such may have happened here, 
complicated by the two nearly concurrent intersecting 
shocks. The centre of gravity appeared to the eye, to be at 
about 2 feet 2 inches above the base, and the weight of the 
statue was about 3 cantari, or 6h to 7 cwt., bat I had no 
means of further examination. The Priure, and still more 
the Vicario, II Padre Bruno SantuUo, were enabled to give 
me an intelligent and consistent account, of their experience 



TESTIMONY OP THE MONKS. 397 

and observations during the earthquake. They, and all 
with whom I conversed in the monastery, described the 
noise as being heard at the same moment, as the first move- 
ment of shock ; some thought a very little before, some an 
instant after, and that it continued as an awful rumbling 
roar during the whole time of motion, and even after it. 
They could give but a very confused account of the second 
shock, which arrived about an hour after the previous ones ; 
saying that they were all in too much alarm, and dread of 
the buildings around them, that were momentarily giving 
signs of falling, to be prepared to remark much about the 
last shock, except that it further ruined and shook down 
many things that the preceding ones had left. They had 
all taken refuge in the centre of the great open court, and 
remained exposed to the cold for several hours, before they 
durst return to their shattered cells. 

They were unable to give any precise information as to 
the moment of occurrence of the first shock ; and as to 
direction, they could only say they were shaken in every 
direction, and that the shocks were at first, they thought, 
from north or N. E., and then in every way or vorticoso. 
The only watch in the monastery, was a curious old English 
one, the maker's name and date in which proved it to have 
been made about 140 years before ; and with a singular 
notation for the hours upon the dial, which the owner had 
never been able to make out until I deciphered it for him. 
It may therefore be imagined that it was not kept very 
exact as to time, and probably had not for a hundred years 
shown true time, until the day when I set it at noon, for 
the venerable and simple-hearted owner. 



CHAPTER XVI. 

PADULA TO MOLITERNO, BY THE PASS OF ARENA 

BIANCA AND LAGOMAOURI. 



I LEFT my kind hosts of the Certosa at early dawn, on 
the 16th February, to pass still further south in the valley, 
and ascending over the pass of Ovedone, or Arena Bianca, 
to reach Molitemo, in another valley to the south-east. 

Approaching Sassano, a town on the west side of the 
valley, four miles from Certosa, I was enabled to see with 
the telescope that it had suflFered but little, as was also 
the case with St. Giacomo, to the west of it. One building, 
partly ruined, and above the level of others, I could see 
distinctl}% and by the fortuitous circumstance of the 
light from the sun reflected from its window-panes, whose 
azimuth I observed, was enabled to calculate approximately 
the axial line of building, and to infer the direction of the 
fractures and of the shock there. It turned out to be 
137*^ E. of north. I cannot lay much stress on an observa- 
tion so made. The muleteers, who knew the place well, said 
the people of it believed the great shock to have been 
from north to south, and that the same was the case with 
Biiouabitacola, a small village at the same side, but further 
south. I passed near the latter, and the muleteei's pointed 
out, where some large fissures had been produced in the 



ASCENT OF THE PASS. 399 

earth near the road. I could not spare time to visit either, 
and commenced the ascent towards Ovedone, the mules 
creeping up, by stony traverses, along the N. E. side of 
the Fiume Imperatore, a torrent falling into the Galore, 
on its right bank. The section of the mountain range 
crossed, which separates the valley of the Galore, from 
that of the Moglia and Agri, and the general features 
of its geology, so far as I could observe them along my 
mule tracks, and thence on to and beyond Montemurro, are 
given in the section, Diagram, No. 241, Fig. 1. 

After three hours' ascent, the form and features of the 
surrounding amphitheatre of mountains, by which the 
Vallone of Diano is shut in southward, became well dis- 
played. To the south-west, stretching away above two 
miles, the Bosco della Gerzeta, is beneath me. The little 
town of Gasalnovo, which is said to have suflfered but little, 
is just visible beyond it, and high above, at some ten 
miles away, the gigantic Monte Cocuzzo, and further west 
Monte Rotundo, with Monte Gervaro due south, both of 
massive grandeur in outline, rise above innumerable lower 
peaks and hills, and shut in the view. I am 3,000 feet 

• 

above the sea, but still these lofty summits subtend a con- 
siderable visual angle above my horizon. We are here 
upon the southern edge of the region, of actually ruined and 
overthrown towns, the meizoseismal, as reference to the 
Map, B, will show, all those further to the south being merely 
fissured, more or less severely. And from this elevation, it 
is easy to see and understand the physical features of the 
country, that have produced this sudden reduction of effect, 
by the prodigious loss of vis vivdj that the wave of shock 
coming south must have sustained, by the abrupt lowering 



400 TOWNS FAR SOUTHWARD— MONTESANO. 

of the east range of mountains of the Vallone di Diano, 
almost amounting to a local extinction of the ridge at 
Padula ; as well as by its entire change of direction, and 
breaking up into numerous detached masses, after passing 
the low lying intervening gap. 

The residual wave entering the new mountain system, 
has still had power to do great mischief. Casalnovo, Sauza, 
Casella, Podaria, Le Celle, Montano, Laurito, Policastro, 
Lagonegro, (where I learned at the Certosa facts proving 
that the wave-path was there north to south), Rivello, 
Bosco, Lauria, (where the wave-path was also north to south), 
Trecciena, Maratea, Tortora, Ajeta, and down to Casalito 
twenty-seven Italian miles south of where we stand, and 
innumerable other smaller places between, have been more 
or less shattered, though no lives have been lost south of 
Montesano. 

The latter town is high and close above me, a little to 
the south, perched on the crest of a conical hill, well but- 
tressed, and connected with the mountain ridge and 
shoulder on which it stands beetling to the north. As I 
pass, close and beneath it, 1 find from some people of the 
hamlet of Arena Bianca, (a little to the north), that a few 
houses and other buildings, and three churches, have been 
partly or wholly thrown down ; and in the clear morning 
light, with the telescope of the theodolite, I can observe 
the fissures of many of the buildings, and, by the aid of 
the compass, approximate to the /?a^A of the wave, (though 
neither its direction nor emergence). I judged it to be 
from loO"" to 165° E. of north. Near as Montesano seemed, 
I found it would lose 2J hours to climb up to it. 

The brilliant sunlit dawn, gradually got overcast; a 



FENCES AT OVEDONE. 401 

strong wind from the N.W. sprang up, and the remainder 
of the day's journey, and that of three succeeding ones, 
was made under torrents of unceasing rain, which swelled 
the mountain streams, and the great rivers besides, and 
rendered their passage occasionally perilous to the laden 
mules. 

At Arena Bianca, from which the pass over the shoulder 
south of Monte della Vajana takes its name, though called 
indiCFerently that of " Ovedone," two houses are down, 
and numberless breaches are visible, by lengths of the 
drystone fence walls which abound here, (like those in the 
limestone country of the west of Ireland,) having been 
prostrated ; almost all the walls down ran east and west ; 
a few, however, had run north and south, and aflForded evi- 
dence, that while the main wave-path was still nearly north 
to south, there was here, also a minor transverse shake. 



VOL. I. 2d 



CHAPTER XVII. 



JOURNEY OVER THE PASS AND BY LAGO MAORNO. 



As we had ascended, the soft, ill-bedded limestone of the 
lower roots of the hills, had gradually given way to indu- 
rated liBsaicrlookbiff hard, elastic, cherty beds of yellow 
limestone, in distinct and highly-inclined layers, probably 
metamorphic (see Section) — these, after many alternations 
came back to the same solt^ cretaceous-looking stuff, and are 
finally lost, (as we top the steep and get upon the more level 
table of the shoulder and elevated valley), under a deep loose 
deposit of almost perfectly pure and fine white sand, (from 
which the pass and town derive their name), mixed largely, 
but unequally, with impalpable chalky particles. This 
extends to beyond Tardiano, under the southern summit 
of Monte Vajana ; but at various points the rock beneath 
might be seen, and proved that we had lost the limestone 
proper, and got upon an endless succession of thin beds, 
all more or less metamorphic, consisting of ash-yellow 
limestone, often highly quartzose, hard and elastic, alter- 
nating with thick and thin beds, of gi'ey and purple and 
green clays, and of variegated marls ; and in one place some 
beds of 4 to 6 feet of impure alabaster, all highly inclined. 
(Geolog. section. Diagram No. 241.) 
At the highest point of the pass, near Arena Bianca, 



t 



GEOLOGY OF THE PASS. 403 

the barometer stands at 26'50 inches, thermo. 42'' Fahr. 
at 12"30 P.M., and the elevation above the sea at Naples 
is 31583 feet. At Tardiano, the contrary slope towards 
the valley basin of the elevated mountain lake, the gloomy 
Lago Maorno commences. This lake is commonly pro- 
nounced Lago Maouri by the peasantry. Many singular 
beds of metamorphic shales, and indurated clays, with some 
thin seams as hard as chert or jade, and, lithogically, very 
like the latter, are passed, and at about 500 feet above the 
level of the Lago Maorno, where the descent has become 
again very steep, along by the northern side of a nameless 
torrent that discharges into it, great beds of intensely 
hard, flinty, and haematitic, dark-blue grey limestone occur, 
with huge seams of very hard, black and brown haematite, 
12, 15, 24, and 30 inches thick. All these run here in 
a general direction, for a considerable way, nearly east 
and west, but as they extend, are much twisted to- 
wards the north. They are very nearly vertical, their dip 
being only 15° to the south. The torrent separates these 
beds to the south from the cretaceous limestone, which here 
makes its appearance once more. Sloping up steeply 
to the north for more than half a mile, with a bare, wea- 
thered, and water-furrowed surface, without a blade of vege- 
tation, extend parallel, and nearly vertical beds of green, 
grey, and purple clays, alternating with beds of yellow, 
soft, clayey sandstone, many yards in thickness, standing in 
ridges high above the worn-down clays. (See enlarged 
plan and section, Diagram No. 242.) My attention was 
directed, in particular, to these beds of ferruginous rock 
here, by fiading that the compass would no longer work, 
the needle turning round 90°, within a few paces' change of 

2 d2 



404 GREAT ROCK FRACTURES 

position. On examining the hard ferruginous beds, of 
thick, blue grey, flinty limestone at A (plan and section) 
I found, with some surprise, that they exhibited at the 
exposed south face, for about 200 feet in length, numerous 
large fresh-made fractures, running nearly vertically, right 
through the whole of the strata, up to the dense but soft 
clay beds to the north. Further to the east the beds are 
covered up by clays on both sides, and the ends of the 
strata alone visible. These were much obscured by the 
torrents of creamy clays that the rain was washing over 
them ; but yet I was enabled to trace similar fractures 
across the tops of the beds, and extending vertically down- 
wards through them, for a distance of about 250 yards 
eastward. To the westward, the torrent runs through these 
indurated beds, and cuts oflF those to the west of it from 
any contact visible with the clays. 

At the base of the vertical beds below A, in the bed of 
the torrent, great masses of freshly-fractured and fallen 
rock were lying, and in several of the fmctures, the widest 
of which was open, on an average, about an inch, on the 
south face, of the nearly vertical beds, I found fresli frac- 
tured splintering fragments in various spots. These liad 
dropped down a few inches only, and I could replace and 
fit them into the spots from which they had fallen in the jaws 
of the fissures. There could be no mistake as to the fresh- 
ness of the fractures, for all the old and weathered portions 
of the rock, were a deep iron rust, in colour ; but the fresh- 
broken surfaces, a bright blue grey, of a deep tint. Many 
large fragments from the tops of the upcrop of the beds, 
had also been detached at weathered fissures, from the south 
iace, and lay thrown into the bottom of the torrent. 



DUE TO THE EARTHQUAKE. 405 

It was unmistakably obvious, that the fractures had been 
produced by the transit of the earthquake, and that the 
push, of the vast piled-up mass of comparatively soft heavy 
clay beds, &c. to the north with which they had been 
forced against the barrier of these hard limestone beds that 
ramparted them in, had been of such force as to fracture 
the latter in many places. The hard unyielding rock had 
broken ; the softer clay beds had merely been slightly com- 
pressed, and changed insensibly in form ; hence they pre- 
sented no evidence of the force that they had transmitted 
to the fractured rock. On ascending the slope of the claj" 
beds, northward about 500 yards, however, I found con- 
firmatory evidence of my conclusion, in great masses of 
fresh fractured and fallen sandstone from the thick beds 
at C. (Diagram No. 242.) 

The N.E. face of the deep gorge beyond C, not shown in 
diagram, that brings another torrent down in a N.W. to 
S.E. direction, also showed great falls, of these soft sand- 
stone cliflFs in the bottom. I had great difiBculty in 
descending the wet clay beds, which, devoid of a single 
pebble, presented no foothold whatever upon their unctuous 
and slippery slope, and a fall produced much the efiect, 
of being dipped into a succession of paint pots. 

This fact was to me one of peculiar interest : it was the 
first example I had found, of actual fracture of beds of hard 
rock in dtu, by the impulse of an earthquake wave — a 
phenomenon in kind totally distinct, from such breaking off 
of great masses, as the rock falls of Campostrina, or the 
Arguilles of Padula. Here were beds of the very hardest 
and toughest rock, such as, with difiiculty, I broke spe- 
cimens from, with the hammer, fractured for many yards in 



406 LAGO MAOUNO— MONTfi RAPARO. 

depth (fully thirty yards was visible) and extending over 
a great length of bedding, and yet free from any other sign 
of violence, or any other sensible disturbance of position. 
It realized forcibly to the mind the enormous power of 
the impulse of shock with even this moderate velocity when 
acting at once upon great masses, at free or outlying sur- 
faces ; and is suggestive of the much more potent effects, 
that must be occasionally produced in loftier ranges, 
subject to still more powerful impulses. Hooker's account 
of the rock dislocation witnessed by him in the Hima- 
layan shocks recurred to mind. Strictly interpreted, how- 
ever, even this, is -but an example of dislocation by 
secondary effects, of the wave, not by the wave itself. 

The Lago Maorno now comes into view, a dreary pool 
of about a mile long by half as much wide, in the midst of 
a mountain basin, surrounded with deep tenacious clay soil, 
apparently of great fertility, but swampy and wet. Across 
this the mules passed with much labour, sinking nearly 
to the knees. The shallow valley basin, devoid of tree, 
house, or human being, is surrounded with low barren hills, 
all apparently of soft limestone, those to the eastward of the 
lake, coming down close and abrupt to its margin. Above 
and beyond the hills to the N.E., Monte Spagnoletto rises 
high, and powdered with snow ; and far away to the S.E., I 
see the lofty summits of Monte Raparo, and Monte Armiz- 
zone, deeply covered with it, as well as the intervening 
ridges. 

All attempt to cross these now, and gain access to 
Castel Saraceno, Chirico Raparo, Carbone, Calvera, La- 
tronico. Episcopio, and many other towns lying deep iu 
the mountain recesses, far to the S.E. and east, I found 



DESCENT BY THE SCIAVRA. 407 

would be impracticable. All these towns, and many others 
around them, had suffered severely. 

At the margin of the Lago Maorno, the barometer marked 
27*10 inches, thermo. 42"^ Fahr. at 3 p.m., and the surface 
of the lake I find to be 2526 feet above the sea, at Naples. 
Crossing the piano, or basin of the lake, we ascend again, 
cross the Serras, of Cerzuto and Pizzuto, and on the ridge 
of the latter gain the first view of Moliterno, and dimly dis- 
cern through the rainy atmosphere, Sarconi, Spinosa, Vig- 
giano, Marsico Vetico, and even Montemurro, all towns, 
nearly or quite destroyed. We now commence to descend, 
by the side of the highest fork of the Fiume Sciavra, which 
falls into the Agri, along the east flank of a wild and grand 
ravine, with the torrent in the bottom, which, in its now 
swollen state, seems to be sweeping bodily before it, masses 
of the beds, of red and yellow clays and marls, and calca- 
reous detritus, that to a depth of 30 to 60 feet form its 
boundaries, and conceal the formations beneath the sloping 
plain, the Piano of St. Martine. 

At the highest point I passed upon the Serra di Cerzuto, 
the barometer stood at 26*65 inches, thermo. 45° at 
5*". 5°. P.M. Naples time. The height above the sea was 
2994-4 feet. 



CHAPTER XVIII, 



MOLITERNO. 



A RAPID descent by a pretty good track, brought us to 
Moliterno, about an hour after dark, wearied and wet, after 
more than fifteen hours* walking and riding, twelve of 
which had been under heavy rain and wind. The Locanda 
here, though much shattered and in parts unsafe, was still 
tenantable, and I deemed myself happy in finding shelter 
and fire, for myself and my party. 

Molitefno stands upon a low hill of hard and dense lime- 
stone, but generally without distinct evidence of bedding ; 
in some spots to the east of the town there are indications 
of beds dipping to the west, with a moderate slope. The 
bill slopes rapidly towards the Sciavra, upon the south of 
the town, where are the ancient mills from which it derives 
its name. Monte Spagnoletto stands due north, and a little 
to the N.W. of it, distant about 2| Italian miles, while 
round thence to due west are the ridges of the lower Serras 
that shut out the high table land and basin of Lago Maoruo. 
The town, situated in the midst of rich valleys, seems a 
thriving place. Several large modern buildings have suf- 
fered but little, and there are some in progress of erection. 
The people here show no lack of energy in clearing away 
the effects of the earthquake, which, however, has dealt 
very mercifully with them, in comparison with towns not 



THE CHIESA MADRE— THE CASTELLO. 409 

five miles away. At the Locanda, situated in the higher 
part of the town, the barometer at 8-30, Naples time, 
17th Feb. reads 27*05 inches, thermo. 51° Fahr. : it is 
2696*7 feet above the sea. The highest point of the 
CoUine on which the Castello is situated is about 200 feet 
above this, or nearly 2900 feet the summit. 

In the new buildings in progress here, the causes of such 
facile destruction by shock as I have remarked, are patent ; 
no thorough bond, thick and heavy walls of ill-constructed 
rubble, floor beams a yard apart, inserted only 9 inches 
into the walls, without " tossals " or wall-plates, want of all 
mutual connection between the walls, floors, and roof, and 
both the latter of prodigious weight. 

The Chiesa Madre has its axial line nearly north and 
south, built of brick, with limestone pilasters, &c., and brick 
vaulted roof, about 160 feet by 45 feet wide and 60 feet 
high to the springing of the vault. The transepts are 
vaulted also. The arch is semicircular, and is fissured 
widely, down to the springing, and open an inch in places. 
The fissures in the walls, are fine and narrow, but give 
good indications ; general direction of wave-path, from 140° 
to 145° E. of north, and the slope with vertical 10° to 12°, 
giving ^ = 11° from the N.W. 

Nothing to indicate velocity. All around the church, 
are many ordinal buildings, fissured and partially thrown, 
and one large cardinal one, all of which indicated more or 
less distinctly, a wave-path from some point to the west of 
north to south ; there were evidences, but obscure, of a 
minor and nearly orthogonal wave. 

The Castello, consisting of heavy old massive masonry, 
much indurated, is severely fissured. Gkneral direction, 154° 
or 153° 30' E. of north, but the extreme limits are very wide 



410 GHIESA DELLA KOSARIO. 

here, viz., from 105° to 1G5° E. of north. I have not taken 
a mean, but a choice^ of those fissures whose direction ap- 
peared least likely to have been influenced by curvature 
(as in the great round towers) or other disturbing con- 
ditions. The fissures in the great towers of 80 feet in height 
or thereabouts, were open 2 J inches at the top. The walls 
were very thick, and such that this width, is a rude indica- 
tion of the amplitude (horizontal) of the wave here. 

The Ghiesa, della Santa Dominica della Eosaiio, has its 
axial line 120° E. of north, or not far fix)m cardinal : it is 
about 160 feet long and 50 feet wide, with a brick semi- 
cylindrical vaulted roof, 40 feet to the sofiBt, which, with 
the walls, are heavily fissured : the mean of seven pairs of 
these, gives a general wave-path of 155° E. of north, and 
an emergence fi'om the north of 13° 30', the extreme limits 
being 10° and 17°. In this building there is evidence also 
in the vault fissures, of a subordinate shock, nearly at right 
angles to the main one. 

On altars, both at the north and south sides of the 
church, I found wood gilded candlesticks, that had been 
thrown out of plumb. Those on the north side had been 
thrown towards the N.W. at various angles, and still leaned 
against the back wall or shelf of the altar. They were high 
up and out of reach. Those on the south of the church, I 
found now in their usual places, but the Sacristan informed 
me, that all the wood candlesticks at that side, had been 
thrown quite ofif the altar, and were found scattered about 
the floor, and had been since replaced. 

These are decisive as to direction of the wave here, viz., 
from a point W. of north towards the south. The candle- 
sticks at the north side, thrown by the first semiphase of the 
wave, were limited in motion, by the wall against which 



GAETANO MALLIONE'S BOTTLES. 411 

they fell and leaned, having gone over too far to recover 
their position at the return stroke. Those at the opposite, 
or south side, were at the same moment thrown out of 
plumb forwards, or towards the front of the altar, and find- 
ing no wall to support them, fell altogether. 

In the CaflFe of Gaetano Mallione, a number of bottles of 
the form of foreign wine bottles, full to the corks of Rosolio, 
stood upon a shelf, at 8 feet high from the floor, running 
along the west side of a wall, whose length was N. 155° east. 
The owner, an intelligent fellow, replaced the bottles for 
me in the position in which he stated he had found them 
in the morning after the shock. (Sketch No. 243, Coll. 
Roy. Soc.) Those towards the back of the shelf, (which 
was about 15 inches wide), leaned back against the wall, 
and against each other, sloping towards the east and south. 
Several that had stood upright close to the edge of the shelf, 
(which had a little ledge or curb of about three-quarters 
of an inch high, rising at its front edge), had been pitched 
over and thrown upon the floor and broken. The spots upon 
which these had landed, I found were on the average, three 
feet horizontally from where the bottles had stood on the 
shelf. The direction of throw was about 125° E. of north 
towards the N.W. ; omitting one, thrown in the apparent 
direction xU>y. 

If we assume the emergence to have been 15"^ here, we 

have 

e = 15^ a = 3. 6 = 8. 

and the normal velocity of the wave here given by the 
equation 

J «^ 9^ 

V = sec ^ x/ T ; x \ 

V 6 — rt tan (? 2 



412 SECOND SHOOK— SOUNDS. 

is 10*8 feet per second, neglecting the velocity necessary 
to upset the bottle from its base, which should be added, 
and would increase the velocity per second a foot or two. 
We cannot rely upon this for more, than a general indica- 
tion, that the velocity here was not materially different 
from further west and north, and I could get no better 
data at this town. 

I could obtain but very confused accounts here, of the 
second shock, (that of an hour or so after the great one,) 
many persons saying they did not feel any such, nor could 
I obtain any good account of the sounds ; all agreed that 
they heard the " rombo." I was unfortunate, however, in 
not being able to find the Syndic or Judice, both of whom 
were absent. 



CHAPTER XIX. 

SARCONI. 



I LEFT Moliterno at noon for Sarconi, still in heavy rain, 
with a cold N.E. wind. This town, a place of extreme 
antiquity and probably of Greek origin, is not above two 
Italian miles, in a right line nearly, east of the fonner, 
crossing the valley of the Sciavra. It stands on the lowest 
level of the piano, probably 700 feet, if not more, below 
Moliterno, upon the very edge of the steep and lofty bank of 
about 100 feet in depth, of deep alluvium and clays, over- 
hanging the north bank of the Moglia, here in winter a large 
river, whose stony bed is at least 700 feet wide. It is 
spread out at the town upon horizontal beds of green and 
grey thin-bedded marls, with calcareous breccias and deep 
clays above. (See Gkolog. section. Diagram No. 242, and 
Sketch, section. No. 244.) 

Directly to the N.E. side of the town, a low coUine of 
limestone rock rises to the height of about 350 feet above 
it, the hard and nearly horizontal beds of which, pierce up 
steep and abruptly through the clays, &c. This colline bears 
round the town a good way, east and north. (See section. 
Sketch No. 245.) The opposite, or right bank of the 
Moglia shows limestone in highly inclined beds in some 
places, and covered with deep alluvium. 



OKOLOGY OF THK MOGLIA. 



Photog. No. 246 (Coll. Roy. Sec.) gives a good notion 
of the position of the town, and that No. 247, (Coll. Roy. 




Fig. 245. 

Soc.) of the character of the horizontally bedded limestone 
fonnd hereabouts, as well as that of the right bank of the 
Moglia. The town is situated on the tongue, between the 
Sciavra aud the Moglia, and fram the general direction of 
wave-path hereabouts, the blow must have been delivered 
to it, diagonally transverse to the tongue of land, and from 
the limestone masses to the east and north, and was neces- 
sarily severe. From this, from the antiquity of very many of 
the buildings, and their ill construction, their ruin is great. 
The fallen houses and hills of debris are perfectly un- 
intelligible en masse, but two or three isolated buildings 
only, present fractures or fissures. These gave an average 
of direction, 175° E. of north, but very unsatisfactory, both 
from their character, and from the high wind and driving 
preventing good measurement. 



AHCIENT CHURCH AND ANCIENT PRIEST. 415 

The old charch, however, gave better results. It was a 
building of great antiquity ; the axial line was 55° W. of 
north, and, on entering the western door, I observed that two 
ancient and probably Roman altars, with nearly effaced in- 
scriptions, had been bnilt into the walls, and formed the 
pedestals for the stone jambs of the doorway. The bnildiog 
has wholly fallen in, and in great part the walls are down. 
The belfry tower stood at the north quoin (Phott^. No. 
248), a tower, of about 20 feet square, of which about 47 
feet in height remain standing. The whole of the upper 
part has been thrown down, and the mass has fallen, partly 
within and partly without the church, and some on the 
highest remaining floor of the tower itself, all falling towards 
the S,B. There was a single bell in the tower, of about six 
cwL, which hung, as the " Parrochiano" (an aged priest, 
who politely came out in the rain to give me information, 
and whose name, I regret to find, I omitted to note) 
informed me, to a beam in the centre of the tower, and at 




a height of 30 palmi above where I found it ; namely, lying 
upon the top remaining floor, amidst rubbish and fallen 



416 THK CHURCH BELL— WAVE AMPLITUDE HERE. 

timbers, with its mouth facing S.E. The centre of gravity 
of the bell, was 7 feet horizontally, distant from the centre 
of the tower, and the direction of its throw from the 
centre of the tower was 149'' E. of north (Fig. No. 250). 

This direction, I found coincided closely with that given 
by fissures, Photog. No. 249 (Coll. Roy. Soc), two pairs 
of which gave a wave-path of 145° E. of north, and an angle 
of emergence from the N.W. = 16° 25'. This angle, as 
given by the isolated buildings before adverted to, appeared 
to be but 11° to 11° 30' ; I rely, however, upon those of the 
church. 

The bell had fallen vertically 30 palmi=30 x 0*862 ft.= 
nearly 26 feet English. We have, therefore, 

e = 16°-25' a = 7 6 = 26, 

and the value of 

V = 9*78 feet per second ; 

a result necessarily below the truth, as the effort of the 
wave, was communicated to the bell, not through the centre 
of gravity, but by the pintles ; so that the first effect, was 
merely to make it siving^ contrary to the direction of throw. 
We may estimate the velocity as at least 2 feet per second 
more, or about 12 feet per second for the wave here, which, 
although not exact, sufficiently corroborates previous deter- 
minations. 

Several very thick and very ancient walls here, built of 
small bad rubble, and showing themselves to have been 
very dead and inelastic, presented quoin fissures, open 4|, 
5, and oven 6^ inches, at 20 to 30 feet from base ; the 
average might be taken at 4f to 5| inches, and seem to indi- 
cate a wave of long amplitude here. 



CHAPTER XX. 



SARCONI TO SAPOXARA. 



I LEFT Sarconi, where little could be learned, and pushed 
on by the valley of the Moglla, through about two miles of 
fine oak forest for Saponara. 

Having recrossed the Sciavra, I paused upon the S. E. 
slope of a low hill, south of Saponara, and within half a mile 
of what was a few weeks since, a town of six thousand 
inhabitants, now a shapeless heap of ruin. 

To the west, on the recent ruins of a Capuchin convent, 
under II Monte, and to the east, on the opposite bank of 
the Sciavra, on the piano, in the fork between it and 
the Agri, are the ruins of the ancient Roman city of 
Grumentum- 

The low hill, on which I am, like all those hereabouts, is 
of ill-compacted limestone, in beds nearly horizontal, dipping 
here 10° W., and much covered with deep alluvium. These 
must be reposing perfectly unconformably, against the lime- 
stone beds, of which the lofty and steep conoidal hill upon 
which Saponara stood, is composed. 

These run through the mass of this hill, tilted to within 
15° of vertical, and in a direction, generally, of a few 
degrees to the west of north and south. 

VOL. I. 2 E 






4U P0S1TK>X OF SARWABA. 

The hill itself Is n^ariy ocmnd^ nriJier nairoww in its 
N. E. uid S. W. diameter, than at ri^t angles ttereto : it is 
extnmely steep, and rises tmm 900 to 1000 feet (by the 
eye) above the rirer Agri. 

13ie town corraedtlieBiHamit, and q^ead some waydoira 
the flanks all zonnd, descending most, npon the east side. . 
Tbe ancient Xorman OasteOo Oilliberti, crowned Hie creet^ 
whiGb was bare limeetuie rock, and equally bare for 200or 
SOO.feet downwards. Beds of in<SBasing tJuckness of alln- 
Tinm then begin to cover it, and as it slopes down nqjidly 
at an angle <tf nearly 46** to the Agri, these become 70 to 
100 feet duck. 

The appOBVto bank of the river, mnnlng N. W. to S. EL, 
which I can see abont 400 feet below me, consists of still 
deeper aUavinm, fonning part <3i the Piano Spineto, Ac, 
resting iqmi horizmtal and eipoeed beds ot days and 
schaly argillaceoos rocks. 

To the north and N. W., beyond the hill of Saponara, the 
Piano of Mattine delle Rose, extends for some five or six 
miles, all of snch formations, and beyond that the mountains 
rise to Marsico Vetico, and beyond to the crest of Monte 
Voltorino. It was from this direction that the blow reached 
Saponara — delivered end on through its vertical beds, from 
the vast mass of loose material of the piano. Insnlated to 
a depth of 1000 feet, the Agri and Sciavra running round its 
base from N. W. to south, peaked, narrow, and abrupt, and 
surrounded by horizontally abutting, dense and inelastic 
formations, the summit of the hill and the unhappy town 
upon it, must have shook and swayed like a mast, after the 
shock of the 16th of December. 

The appearance of the ruin of Saponara was appalling. 



APPEARANCE OF THE OVERTHROWN CITY. 419 

As I advanced, and gradually ascended close to it upon the 
S. K, and looking north, literally nothing remained standing, 
upon the crest, but the Castello Cilliberti (Photog. No. 251). 
Its roofs and floors were fallen in, its towers split or fallen, 
and many of its massive, indurated, ancient, and buttressed 
walls prostrated. All the upper part of the town, that 
which had been the most thickly built upon and densely 
inhabited, was now strewed around in featureless ruin ; 
acres of ground were covered and heaped, with rounded 
mounds and sloping avalanches of white and dusty debris, 
but not a wall, or even the base of one, standing or visible. 

Upon the very summit (to the right of the Castello Cilli- 
berti, Photog. No. 251) may be seen projecting above the 
mass of rubbish the solitary fragment remaining erect of the 
ancient church, — a building of enormous solidity, massive, 
and ancient — and whose masonry, indurated by time, 
attested, by the enormous blocks in which some of its quoins 
were dislodged, its resistance to the terrible violence of the 
shock here. These are seen from a closer point of view in 
Photog. No. 252, looking nearly northward. 

It was not, however, until having passed beneath the 
town, to the north of it, and looked back upon it, that the 
awful character of its desolation became fully developed. 

Seen from this side (Photog. No. 253) the summit and far 

down the slope all round, presented nothing but a rounded 

knoll — shadowless and pale — of chalky stone and rubbish, 

without line or trace of street or house remaining ; it might 

have seemed an abandoned stone quarry, or the rubbish of 

a chalk pit, save that its rounded and monotonous outline, 

was broken here and there by beams and blackened timbers 

that rooted in the rubbish stood thrown up in wild confusion 

2 E 2 



420 THE UTTER DESTRUCTION DUE TO 

against the sky like the gaunt arms of despair.* Such an 
horizon high above me, and close around, on all sides the 
cold and dripping huts, thrown together, of whatever ruin 
'had first presented to the hand, and filled with wounded 
and perishing beings, depressed the spirits of even the pass- 
ing observer, to an extent that made me readily compre- 
hend, the dull and stupefied patience, with which the sur- 
vivors still cowered round the ruin of their homes. 

There was less of the town upon the north, than upon the 
south slope of the hill ; and as the blow came from the 
N. W., the " free lying stratum" was at the south and S. E. 
side, so that the condition for destruction, and the extent of 
food for it, were both here the greatest possible. 

The only portion in which walls were standing at all, and 
still showing something of the features of a town, though 
shattered and in great part roofless, was at the east side, a 
long way down from the summit, as seen in part in Photog. 
No 251, and in Photog. No. 254 (Col. Roy. Soc.J, from 
the east side, looking back westward and northward. 

No more complete proof could have been afforded of the 
fact, that the utter destruction of the town was due to the 
swaying of the hill itself upon which it stood, and not to 
some great increase at this region, of the dimensions or velo- 
city of the earth-wave itself, than the finding several build- 
ings around the base of the hill, and upon the deep alluvium 
close to its junction with the limestone of which it is com- 
posed, comparatively safe — all, however, severely shattered. 
Of these an example occurs in a house of two stories, seen 
to the left and low down in Photog No. 253. 

* These timbers bad been removed for huts and fuel between the time of my 
visit aud that of takiiii^ the photographs, February to May, 1857. 



THE MOVEMENT OF ITS HILL SITE. 421 

The Castello, and the portion of the town below it to 
the east, gave abundant measures, of direction and emer- 
gence. The wave-path was sub-abnormal to almost every 
building in the place, and vast wedge-shaped masses were 
thrown out everywhere, some of which may be seen in 
the Photographs. 

The examination of the buildings of the Castello resulted 
in a wave-path 150° E. of north to south, and an emergence 
of 14° to 16° from the north. 

The buildings on the east slope gave a rather diflferent 
wave-path ; the average of a great many giving 120° 30' 
E. of north, and a less emergence 12"* to 15° from the north. 

I take the former, however, as the true wave-path here, 
and deem the diflference lower down to arise from the gyra- 
tory oscillation of the hill itself. A further proof of this 
was, that on traversing round its base, I found that while all 
the buildings there situated, gave a prevalent direction of 
wave-path about the same as above, they also showed com- 
plicated secondary fissures in directions that indicated their 
production by oscillations, emanating everywhere radially 
from the centre of the hill. I conclude, therefore, that the 
first great blow which prostrated in a moment the town, 
came as above. The hill itself, set to oscillate in the same 
plane as that of the path of the wave, rapidly began to 
oscillate in other planes, in fact, became a conical pendulum, 
and hence whatever buildings remained standing but fis- 
sured, by the primary blow, were again fissured in new 
directions or prostrated by this proper motion of the mass 
of the hill. 

There were even evidences in the Castello at top (where 
these secondary motions were, of course, a maximum) of 



422 VELOCITY OF THE SHOCK CALCULATED, 

portions that had been broken out and disjointed, in the 
direction of the original wave, and by it, having been 
thrown afterwards, in directions nearly orthogonal to it 

.It was difficult to get any indication, from which to 
calculate velocity here, or any approximation to the ampli- 
tude of the wave, nearly everything being totally prostrate 
and the history of its fall, a blank ; the bells, for example, 
of the church, were many feet deep under stone and rub- 
bish. 

The direction of the wave being generally sub-abnormal, 
rendered it difficult to find any walls at the Castello, directly 
across the plane of which, the force had passed, and so cir- 
cumstanced, that, being found still standing, they would 
afford to calculation, a limit beyond which, the total velocity 
of the summit of the hill could not have reached. In fact, 
had the wave and first oscillation of the hill, together been 
normal or subnormal to the walls of the Castello, not one 
stoue of it would have been left standing ; its remnant 
owed its remaining erect, mainly to the diagonal direction 
of its walls in reference to the wave, as may be readily 
seen, in the case of the buttressed curtain wall to the left 
in Photog. No. 251. 

I was enabled, however, to find one massive piece of 
wall at the north side, whose condition admitted of its being 
used as a tolerable measure of this limiting velocity. Its 
lengthway was 72^ E. of north ; it was therefore within 12'' 
of being transverse to the path of the primary wave. 

It was a curtain wall of old rubble masoury, connected 
with buildings or towers at both ends about 40 feet apart, 
but in advance of one, so that it had very slight bond with 
that tower ; while at the other an old settlement, or crack, 



AND OF THE OSCILLATION OF THE HILL. 423 

broke a good deal of the connection. This wall was cracked 
nearly horizontally, about a foot above its base, and leaned 
over to the north about 1 i inch. It had no batter : its thick- 
ness was 2*75 feet^ and its height 20 feet. We can calculate 
the horizontal velocity necessary to have fractured its base, 
without overthrowing it, from the equation — 

y-^9>^ ad- 
here b = 2*75 feet; and to allow for the wall being 12° out 
of square to the wave-path, we shall take it = 2*8 feet ; 
a = 20 feet, L = 2 x 52 feet. The coefficient for rubble 
limestone masonry of this highly indurated mortar being 
fully double that of ordinary work. Then 

F= 21-46 X — -^j — = 15-623 feet per second. 

I have no measure of the value of e, for Saponara, except 

those of the Castello, the maximum of which was 16°. We 

may assume it about the same as at Sarconi,= 16° 25'; 

and taking the velocity of the wave itself (in its normal 

direction) to be the same as at PoUa = 12*97 feet per 

12*97 

second, we have its horizontal velocity = = 12*45 ft. 

sec e 

per second ; deducting which from the preceding, we obtain 

3*173 feet per second as the velocity of oscillation of the 

hill of Saponara itself, which may be considered as having 

been horizontal in direction. 

The extreme limit of total velocity then, at Saponara, 

cannot have exceeded about sixteen feet per second, only 

about three feet per second greater than at PoUa, Padula, 

« 

&c. — a striking proof how small an increment of velocity, is 
sufficient to sweep all before it. 



CHAPTER XXI. 

SAPONARA TO SPINOSA, AND THE ENTRANOE OF THE 

VALLBY OP THE LADERANA. 



Leaving Saponara, where there were no authorities bat a 
few gendarmes to be found, one of whom I took on with 
me to Montemurro, which I proposed to reach hiBj (as a 
guide rather than a protection against marauding on the 
part of the starving people hereabouts,) I rode along the 
right bank of the Agri eastward, to near Hhe jonetion 
with the Moglia, and. then forded the former with some 
difficulty, owing to its swollen state ; and after half a mile 
again forded the Aqua Fredda, or Frigida, which, comiDg 
down by the little vallone of the same name, from the 
heights of Monte dell' Agresto, and the Santo Spirito, falls 
into the Agri on its left bank. Looking back at Saponara, 
from 2 miles distant, to the east, and after crossing these 
rivers again at about 4 miles, I made the sketches (Nos. 255 
and 256) of its appearance and relation to the hills around, 
and to the piano, &c. The aflForested low hill in front, is 
the Bosco di Guardia Maura, and part of the Bosco dell' 
Aspro. The Agri, with deep and precipitous clay banks, 
flows between Saponara and the observer. 

It is scarcely conceivable that Saponara will ever be 
rebuilt, the destruction is too absolute, to leave sufficient 



SPECULAllONS— FUTURE ORGANIC REMAINS. 425 

inducement to remove the mountainous masses of rubble 
and rubbish, that must form the necessary preliminary. 
Those associated with the place will find another site, and 
rekindle their hearths on strange ground, fi^om which their 
surviving successors, will within another century mast pro- 
bably be driven forth, by a future great earthquake, from 
houses as unskilfully constructed, as those their sires 
perished beneath. 

. As I looked back once more upon the place, I came to 
understand that thus it has been, that we find in Southern 
Italy, such numbers of old and new towns of the same 
name, situated not far apart-— such as Corneto, Vecchia e 
Nova, Tito,Vecchio e Nova, Capaccio, Marsico, and numbers 
of others— and it recurred to memory that after the great 
shock of 1783, several of the Calabrian towns, were then 
rebuilt on new sites — as St. Agatha, Vecchia e Nova, 
Bianco, Vecchia e Nova, &c. 

Sir Charles Lyell's vivid sketch, of the probability of 
future ages, finding in the formations of to-day, human 
remains and objects, and records of human art, (' Elements 
of Geology,' chap, xlvi.), embedded and preserved, too, 
suggested thoughts of the future state and after history, of 
the mounds that are alone left where Saponara was. 

Beneath these masses lie, some few mangled human 
remains, that will never probably be found for sepulture — 
those of domestic animals, and of the mammalian and other 
vermin that follow man — fragments of every household 
utensil, personal and domestic ornaments, weapons, tools, 
and instruments, carved and wrought stone, ivory, hard wood, 
grain, fruits, food of many sorts, books, records, crumpled 
pictures, glass and pottery, wrought timber in the splin- 



i26 VELOCITY OF THE SHOCK IN THE 

tered joinery, as well as the metallic parts of houses, Ac. ; 
aoder what changed coaditioDs as to geological position 
may these, if ever, see the light again ! 

In this vitalizing climate, but a few years will elapse, 
before the frosts of winter and its torrential rains, will have 
pulverized and reduced to interstitial soil, much of the dry 
rubbish: plants and seedlings will root in it; forest- trees 
will send their searching roots downwards through it, and 
beneath their fostering shade, a jungle of shrubs, weeds, 
mosses, and coarse grass, will spring up and conceal with 
verdure the harsh colouring and form, of the heaps that once 
were a city ; and after but a few generations the fearful fate 
of its two thousand overwhelmed inhabitants — nay, its veiy 
site, will have become a tradition as dim, as that of the 
neighbouring Grumentum. 

About half a mile S. E. of Saponara, upon the level 
clays of the piano, I passed two square gate-piers of rubble 
ashlar masonry, leading to an orchard, 3 feet square, and 
7 feet in height, both prostrated, and in directions accn- 
rately parallel, 140^ 30' E. of north, fractured at the ground 
level from their foundations. The mortar was bad, and by 
examination with the hand I judged had not an adhesion 




of more than about 2 lbs. per square inch. The wave-path 
was exactly subuonnal to the piers (Fig. 257). 



ADJACENT PLAIN CALCULATED. 427 

The horizontal velocity for frJieture from the equation 

F = I a X —r is therefore 

(r 

V = 5-48 feet per second. 

The horizontal velocity for overthrow after fracture from 
the equation 

e being 22° 40', a = 7 feet, 6 = 3 feet, is 
V = 5 14 feet per second : 

The total horizontal velocity for fracture and overthrow 
is therefore 

V = 5-48 + 5-14 = 10-62 feet per second : 

but e = 16° 25' assumed the same as at Sarconi ; there- 
fore 

V = 10*62 X sec ^ = 11*04 feet per second, 

the actual velocity of the wave in its direct path. This 
result — deduced from two similar blocks of masonry, of the 
simplest and best form, natural seismometers in fact, and 
coinciding so closely with previous and distant determina- 
tions — affords a strong confirmation of the correctness of the 
explanation given, of the nature of the higher velocity that 
overthrew Saponara, close to which, but down on the level 
of the plain, we see thus the wave has its ordinary velocity, 

I pursued my way towards Montemurro, where I hoped 
to rest. 

At 4 miles S. E. of Saponara, under Spinosa, on the 
level of the bed of the Agri, at 3^ 15°" Nap. time, the baro- 
meter read 29*11 inches, thermo. 42°, and gives the height 
above the sea = 649*1 feet. 



428 ENORMOUS RIVER EROSION. 

This may be viewed as about the lowest level of the 
Piano Mattine, so that its mean level is nearly the same, as 
that of the great Piano of Diano. 

For some miles about the junction of the Moglia and 
Agri, evidences of prodigious river erosion exist. In many 
places in the main river-bed — here from 500 to 700 feet, 
or upwards, in width, though rarely covered wholly with 
water — great insular masses challenge astonishment, by the 
rate at which they are being carried bodily off in 
winter. 

One of the more remarkable of these is seen in Sketch 
No. 258: they all consist of great beds of calcareous 
breccia, resting conformably upon perfectly level deep beds 
of extreme thinness of parallel lamination of green, grey, and 
purple clays, or marls, hard, dense, and unctuous, but rapidly 
softened and dissolved when wetted. Above the breccia, 
lies an immense thickness of dense red brown, clay and 
loam ; the laminated marl beds exist, just at the level of the 
watercourse of the two rivers, and as these get rapidly sapped 
and cut away, huge masses of the breccia, break off and fall 
separate into small pieces, and with the clays shed off their 
summits, are swept away, leaving nothing deposited finally 
upon the river-beds, but the harder calcareous pebbles and 
boulders of the breccia, and those still harder travelled 
boulders, which it contained in abundance. Amongst the 
latter, are many of sienite and yellow granites, some of a 
green and white fine sandstone breccia, having lithologically 
a most suspicious look of indurated chalk, from a green sand 
formation, and many of variegated jaspers. Large blocks 
of the latter, banded with green and purple, are found 
abundantly in the clays and on the slopes to the north side 



SPINOSA— CASTEL SARACENO. 420 

of the valley, and are plainly the product of intense meta- 
morphic action, upon the variegated marl-beds. 

Passing beneath Spinosa, I scanned the town narrowly 
with the telescope; but although many buildings were 
prostrate and fractured, it did not appear to oflfer much, to 
reward the time and labour of ascent ; and being only about 
five miles in a right line from Saponara, ascertainment of 
direction here was of less importance. I obtained from some 
houses at the base, however, a satisfactory measurement of 
the latter from fissures, which gave 134° 30' E. of north for 
the wave-path. Owing to circumstances of stone-work and 
apertures, &c., they could not be relied upon as to emer- 
gence, beyond proving that it was from the N.W. The 
owner of one of those houses informed me, that his business 
frequently brought him to Castel Saraceno, about ten miles 
to the south, and that there the shock had been felt from 
N. W. to S. E., or 135° E. of north. 



V- 



CHAPTER XXn, 



JOURKEY TO MONTEMURRO, 



We passed the Agri again, narrowly escaping the loss d 
one of the laden mules, owing to the large stones in tiie 
bed, the torrent of muddy water takii^ them aboTe the 
girths; and commenced a long and toilsome ascent, along 
the small lateral valley of the Fiume Levada^ or Laderana, 
crossing it several times, from the west to the east bank. 

This stream is not named on the maps of Zannoni, or of 
Bachler d'Albe, and no two people hardly, seemed to pro- 
nounce its name quite alike. Once landed on the left (north) 
bank of the Agri, we reach a new set of formations. The 
limestone and breccia here disappear, and are succeeded by 
thick argillaceous beds, with thin bands of something 
approaching to clay iron-stone ; some beds of calcareous 
clays, much indurated, and occasionally, heavy beds of a 
yellow and grey calcareous soft sandstone, all not very far 
from horizontal, and dipping to the north and N. E. The 
whole of these are overlaid, by enormous deposits, of dense 
tenacious clays, red, brown, and yellow, almost without a 
pebble. These stand, as soft shedding cliffs, above this 
stream — now a brawling torrent of liquid mud, which is 
undercutting and sweeping them away, in masses. In many 



LIGNITE BEDS OF THE LADERANA. 431 

places 400 feet in depth of these clays, overlay the soft rocks 
beneath. Near the junction of this torrent with the Agri, I 
had noticed many fragments, and some large lumps of lignite 
in its bed, and when ascended, to within about a mile of 
Montemurro, I was enabled to see the lignite beds in situ 
beneath the clay cliflfs at the opposite (east) side of the 
Laderana, and nearly on the level of the water. They 
appeared to be from 1 to 2 feet in thickness, perfectly 
black, but as fuel, of very inferior quality ; they are un- 
used, and apparently unknown to the inhabitants. 

A good while before reaching this elevation, Gallichio, 
Missanello, and other distant towns, to the east and S. E., 
perched amidst the lateral valley recesses of the Agri, had 
been visible, all showing with the telescope, evidences of 
devastation. St. Archangelo is the most remote, that I 
have had a glimpse of, distant about 20 miles to the S. E. 



END OF VOL. L 



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